[skip ci]Add growing segment detailed insert process doc (#9238)

Signed-off-by: xiaofan-luan <xiaofan.luan@zilliz.com>

docs/design_docs/segcore/segment_growing.md

@@ -1,6 +1,7 @@
 # SegmentGrowing
-Segmentgrowing has the following additional interfaces:
-1. `PreInsert(size) -> reseveredOffset`: serial interface, which reserves space for future insertion and returns the insertion `reseveredOffset`.
+Growing segment has the following additional interfaces:
+
+1. `PreInsert(size) -> reseveredOffset`: serial interface, which reserves space for future insertion and returns the `reseveredOffset`.
 
 2. `Insert(reseveredOffset, size, ...Data...)`: write `...Data...` into range `[reseveredOffset, reseveredOffset + size)`. this interface is allowed to be called concurrently.
     
@@ -8,33 +9,52 @@ Segmentgrowing has the following additional interfaces:
     2. data column can be stored either row based or columne based.
     3. `PreDelete & Delete(reseveredOffset, row_ids, timestamps)` is the delete interface similar to intert interface.
 
-Growing segment stores data in the form of chunk. The number of rows in each chunk is restricted by configs,
+Growing segment stores data in the form of chunk. The number of rows in each chunk is restricted by configs.
 
-Rows per segment is controlled by parameters `size_per_Chunk ` control
+Rows per segment is controlled by parameters `size_per_Chunk ` config
 
-When insert, first allocate enough space to ensure  `total_size <= num_chunk * size_per_chunk`, and then convert data in row format to column format.
+When insert, first allocate enough space to ensure  `total_size <= num_chunk * size_per_chunk`, and then convert data from row format to column format.
 
-During search, each 'chunk' will be searched, and the search results will be saved as 'subquery result',  then merged.
+During search, each 'chunk' will be searched, and the search results will be saved as 'subquery result',  then reduced into TopK.
 
-Growing Segment also implements small batch index for vectors. The parameters of small batch index are preset in 'segcoreconfig'
+Growing Segment also implements small batch index for vectors. The parameters of small batch index are preset in `segcore config`
 
-When `metric type ` is specified in the schema, the default parameters will build index for each chunk to accelerate query
+When `metric type` is specified in the schema, the default parameters will build index for each chunk to accelerate query
 
-## SegmentGrowingImpl internal paramters
-1. SegcoreConfig contains parameters for Segcore，it has to be speficied before create segment 
-2. InsertRecord inserted data here
-3. DeleteRecord wait for implementation
-4. IndexingRecord data with small index 
-5. SealedIndexingRecord not used any more
+## SegmentGrowingImpl internal 
+
+1. SegcoreConfig: contains parameters for Segcore，it has to be speficied before create segment 
+2. InsertRecord: inserted data put to here 
+3. DeleteRecord: wait for delete implementation
+4. IndexingRecord: contains data with small index 
+5. SealedIndexing: Record not used any more
 
 ### SegcoreConfig
 1. Manage chunk_sizeand small index parateters
 2. `parse_from` can parse from yaml files（this function is not enabled by default）
-   1. refer to `${milvus}/internal/core/unittest/test_utils/test_segcore.yaml`
+   * refer to `${milvus}/internal/core/unittest/test_utils/test_segcore.yaml`
 3. `default_config` offers default parameters 
 
 ### InsertRecord
+
 Used to manage concurrent inserted data, incluing
+
 1. `atomic<int64_t> reserved`  reserved space calculation
-2. `AckResponder` calculate which segment to insert，returns current inserted data offset
+2. `AckResponder` calculate which segment to insert，returns current segment offset
 3. `ConcurrentVector` store data columns, each column has one concurrent vector
+
+The following steps are executed when insert,
+
+1. Serially Execute `PreInsert(size) -> reserved_offset` to allocate memory space, the address of space is `[reserved_offset, reserved_offset + size)` is reserved
+2. Parallelly execute `Insert(reserved_offset, size, ...Data...)` interface，copy data into the above memory address 
+
+   * First of all，for `ConcurrentVector` of each column, call `grow_to_at_least` to reserve space
+   * For each column data, call `set_data_raw` interface to put data into corresponding locations.
+   * After execution finished，call`AddSegment` of `AckResponder` ，mark the space `[reserved_offset, reserved_offset + size)` to already inserted
+
+### ConcurrentVector
+This is a column data storage that can be inserted concurrently. It is composed of multi data chunks.
+
+1. After`grow_to_at_least(size)` called, reserve space no less than `size` 
+2. `set_data_raw(element_offset, source, element_count)` point source to continuous piece of data 
+3. `get_span(chunk_id)` get the span of the corresponding chunk