Add Invocation metric to telemetry documentation (#6566)

* Initial plan

* Add Invocation metric to telemetry documentation

Co-authored-by: jstirnaman <212227+jstirnaman@users.noreply.github.com>

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Co-authored-by: copilot-swe-agent[bot] <198982749+Copilot@users.noreply.github.com>
Co-authored-by: jstirnaman <212227+jstirnaman@users.noreply.github.com>

content/shared/influxdb3-reference/telemetry.md

@@ -42,6 +42,7 @@ how you can opt out.
 - **Instance ID**: Unique identifier for the server instance
 - **Cluster UUID**: Unique identifier for the cluster
 - **Storage type**: Type of object storage being used
+- **Invocation**: How the server was started
 {{% show-in "core" %}}
 - **Product type**: "Core"
 {{% /show-in %}}