feat(influxdb3): add install package command documentation

- Create shared CLI documentation for install package command
- Add Enterprise and Core frontmatter files referencing shared content
- Add --node-spec option to create trigger command for Enterprise
- Update code-placeholders to use new fenced code block syntax

Closes influxdata/DAR#6301

.github/instructions/influxdb3-code-placeholders.instructions.md

@@ -48,23 +48,35 @@ Descriptions should follow consistent patterns:
 
 ## Hugo shortcodes in Markdown
 
-- `{{% code-placeholders "PLACEHOLDER1|PLACEHOLDER2" %}}`: Use this shortcode to define placeholders in code snippets.
-- `{{% /code-placeholders %}}`: End the shortcode.
-- `{{% code-placeholder-key %}}`: Use this shortcode to define a specific placeholder key.
-- `{{% /code-placeholder-key %}}`: End the specific placeholder key shortcode.
+**Syntax**:
+
+- Use the `placeholders` code block attribute to define placeholder patterns:
+  ```<language> { placeholders="<expr>" }
+  function sampleCode () {};
+  ```
+**Old (deprecated) syntax**:
+
+- `{{% code-placeholders "PLACEHOLDER1|PLACEHOLDER2" %}}`
+- `{{% /code-placeholders %}}`
+
+**Define a placeholder key (typically following the example)**:
+
+- `{{% code-placeholder-key %}}`: Use this shortcode to define a placeholder key
+- `{{% /code-placeholder-key %}}`: Use this shortcode to close the key name
+- Follow with a description
 
 ## Language-Specific Placeholder Formatting
 
 - **Bash/Shell**: Use uppercase variables with no quotes or prefix
-  ```bash
+  ```bash { placeholders="DATABASE_NAME" }
   --database DATABASE_NAME
   ```
 - Python: Use string literals with quotes
-  ```python
+  ```python { placeholders="DATABASE_NAME" }
   database_name='DATABASE_NAME'
   ```
 - JSON: Use key-value pairs with quotes
-  ```json
+  ```json { placeholders="DATABASE_NAME" }
   {
     "database": "DATABASE_NAME"
   }
@@ -75,8 +87,7 @@ Descriptions should follow consistent patterns:
 ### InfluxDB CLI Commands
 This pattern appears frequently in CLI documentation:
 
-{{% code-placeholders "DATABASE_NAME|AUTH_TOKEN" %}}
-```bash
+```bash { placeholders="DATABASE_NAME|AUTH_TOKEN" }
 influxdb3 write \
   --database DATABASE_NAME \
   --token AUTH_TOKEN \

content/influxdb3/core/reference/cli/influxdb3/install/_index.md

@@ -0,0 +1,15 @@
+---
+title: influxdb3 install
+description: >
+  The `influxdb3 install` command and its subcommands manage package installations for the InfluxDB 3 processing engine.
+menu:
+  influxdb3_core:
+    parent: influxdb3
+    name: influxdb3 install
+weight: 300
+source: /shared/influxdb3-cli/install/_index.md
+---
+
+<!-- 
+//SOURCE - content/shared/influxdb3-cli/install/_index.md
+-->

content/influxdb3/core/reference/cli/influxdb3/install/package.md

@@ -0,0 +1,19 @@
+---
+title: influxdb3 install package
+description: >
+  The `influxdb3 install package` command installs Python packages for use in InfluxDB 3 processing engine plugins.
+influxdb3/core/tags: [cli, processing engine, plugins]
+menu:
+  influxdb3_core:
+    name: influxdb3 install package
+    parent: influxdb3 install
+weight: 201
+related:
+  - /influxdb3/core/process/
+  - /influxdb3/core/plugins/
+source: /shared/influxdb3-cli/install/package.md
+---
+
+<!-- 
+//SOURCE - content/shared/influxdb3-cli/install/package.md
+-->

content/influxdb3/enterprise/reference/cli/influxdb3/install/_index.md

@@ -0,0 +1,15 @@
+---
+title: influxdb3 install
+description: >
+  The `influxdb3 install` command and its subcommands manage package installations for the InfluxDB 3 processing engine.
+menu:
+  influxdb3_enterprise:
+    parent: influxdb3
+    name: influxdb3 install
+weight: 300
+source: /shared/influxdb3-cli/install/_index.md
+---
+
+<!-- 
+//SOURCE - content/shared/influxdb3-cli/install/_index.md
+-->

content/influxdb3/enterprise/reference/cli/influxdb3/install/package.md

@@ -0,0 +1,19 @@
+---
+title: influxdb3 install package
+description: >
+  The `influxdb3 install package` command installs Python packages for use in InfluxDB 3 processing engine plugins.
+influxdb3/enterprise/tags: [cli, processing engine, plugins]
+menu:
+  influxdb3_enterprise:
+    name: influxdb3 install package
+    parent: influxdb3 install
+weight: 201
+related:
+  - /influxdb3/enterprise/process/
+  - /influxdb3/enterprise/plugins/
+source: /shared/influxdb3-cli/install/package.md
+---
+
+<!-- 
+//SOURCE - content/shared/influxdb3-cli/install/package.md
+-->

content/shared/influxdb3-cli/create/trigger.md

@@ -32,6 +32,7 @@ influxdb3 create trigger [OPTIONS] \
 |        | `--disabled`        | Create the trigger in disabled state                                                                     |
 |        | `--error-behavior`  | Error handling behavior: `log`, `retry`, or `disable` |
 |        | `--run-asynchronous` | Run the trigger asynchronously, allowing multiple triggers to run simultaneously (default is synchronous)                                                 |
+{{% show-in "enterprise" %}}|        | `--node-spec`       | Which node(s) the trigger should be configured on. Two value formats are supported: `all` (default) - applies to all nodes, or `nodes:<node-id>[,<node-id>..]` - applies only to specified comma-separated list of nodes |{{% /show-in %}}
 |        | `--tls-ca`          | Path to a custom TLS certificate authority (for testing or self-signed certificates)                     |
 | `-h`   | `--help`            | Print help information                                                                                   |
 |        | `--help-all`        | Print detailed help information                                                                          |

content/shared/influxdb3-cli/install/_index.md

@@ -0,0 +1,5 @@
+The `influxdb3 install` command includes the following subcommands:
+
+| Subcommand | Description |
+|:----------|:------------|
+| [`package`](/influxdb3/version/reference/cli/influxdb3/install/package/) | Install Python packages for processing engine plugins |

content/shared/influxdb3-cli/install/package.md

@@ -0,0 +1,54 @@
+The `influxdb3 install package` command installs Python packages for use in [InfluxDB 3 processing engine plugins](/influxdb3/version/process/).
+
+## Usage
+
+```bash { placeholders="PACKAGE_NAME" }
+influxdb3 install package --packages PACKAGE_NAME
+```
+
+Replace the following:
+
+- {{% code-placeholder-key %}}`PACKAGE_NAME`{{% /code-placeholder-key %}}: the name of the Python package to install
+
+## Options
+
+| Option | Description | Default | Environment | Required |
+|--------|-------------|---------|-------------|----------|
+| `--packages` | Python package names to install (comma-separated) |  |  |  |
+| `-r`, `--requirements` | Path to requirements.txt file |  |  |  |
+| `-H`, `--host` | Host URL of the running {{< product-name >}} server | `http://127.0.0.1:8181` | `INFLUXDB3_HOST_URL` |  |
+| `--token` | The token for authentication with the InfluxDB 3 server |  | `INFLUXDB3_AUTH_TOKEN` |  |
+| `--tls-ca` | Path to a custom TLS certificate authority for testing with self-signed certificates |  | `INFLUXDB3_TLS_CA` |  |
+| `--plugin-dir` | Location of the plugins directory |  | `INFLUXDB3_PLUGIN_DIR` |  |
+| `--virtual-env-location` | Location of the Python virtual environment |  | `VIRTUAL_ENV` |  |
+| `--package-manager` | Package manager to use for installing packages | `discover` |  |  |
+
+## Examples
+
+### Install a single package
+
+```bash { placeholders="pandas" }
+influxdb3 install package --packages pandas
+```
+
+### Install multiple packages
+
+```bash
+influxdb3 install package --packages pandas,numpy,scipy
+```
+
+### Install packages from requirements file
+
+```bash
+influxdb3 install package -r requirements.txt
+```
+
+### Install with authentication
+
+```bash { placeholders="AUTH_TOKEN|pandas" }
+influxdb3 install package --token AUTH_TOKEN --packages pandas
+```
+
+Replace the following:
+
+- {{% code-placeholder-key %}}`AUTH_TOKEN`{{% /code-placeholder-key %}}: your {{% token-link "admin" %}} for your {{< product-name >}} instance