(DOCS-15272): v5.0 backport for count command in stable API (#1052)

Author: jeff-allen-mongo

source/reference/stable-api-changelog.txt

@@ -41,7 +41,7 @@ The following table describes:
 
    * - :dbcommand:`count`
      - V1
-     - MongoDB 6.0
+     - MongoDB 6.0, 5.0.9
    * - :dbcommand:`abortTransaction`
      - V1
      - MongoDB 5.0

source/release-notes/6.0.txt

@@ -44,7 +44,9 @@ the :ref:`Stable API <stable-api>`:
      - Description
      - Stable API Version
    * - :dbcommand:`count`
-     - Counts the number of documents in a collection or a view.
+     - Counts the number of documents in a collection or a view. (Also
+       available in the Stable API for 5.0-series deployments starting
+       in MongoDB 5.0.9.)
      - V1
 
 To see the full list of database commands available in the Stable API,