DOCSP-53791-clarify-free-space-requirements-for-autoCompact-backport (#14767)

Author: mmaville-mdb

content/manual/manual/source/reference/command/autoCompact.txt

@@ -22,9 +22,10 @@ Definition
    files and continuously runs compaction if there is enough free storage space 
    available. 
 
-   Before you enable ``autoCompact``, run the :dbcommand:`dbStats` command to 
-   see if you have enough available storage space for compaction to proceed. If 
-   the amount of available space returned by ``dbStats`` is less than 
+   Before you enable ``autoCompact``, run the :pipeline:`$collStats` 
+   aggregation stage with the ``storageStats: {}`` option to see if you have 
+   enough available storage space for compaction to proceed. If the amount of 
+   available space returned by ``freeStorageSize`` is less than 
    ``freeSpaceTargetMB``, background compaction has no effect.
 
 Syntax
@@ -155,4 +156,4 @@ You cannot run ``autoCompact`` against a :binary:`~bin.mongos` instance.
 Learn More 
 ----------
 
-- :dbcommand:`compact`
+- :dbcommand:`compact`

content/manual/v8.0/source/reference/command/autoCompact.txt

@@ -22,9 +22,10 @@ Definition
    files and continuously runs compaction if there is enough free storage space 
    available. 
 
-   Before you enable ``autoCompact``, run the :dbcommand:`dbStats` command to 
-   see if you have enough available storage space for compaction to proceed. If 
-   the amount of available space returned by ``dbStats`` is less than 
+   Before you enable ``autoCompact``, run the :pipeline:`$collStats` 
+   aggregation stage with the ``storageStats: {}`` option to see if you have 
+   enough available storage space for compaction to proceed. If the amount of 
+   available space returned by ``freeStorageSize`` is less than 
    ``freeSpaceTargetMB``, background compaction has no effect.
 
 Syntax
@@ -155,4 +156,4 @@ You cannot run ``autoCompact`` against a :binary:`~bin.mongos` instance.
 Learn More 
 ----------
 
-- :dbcommand:`compact`
+- :dbcommand:`compact`