DOCS-15357 Count how many pooled connections are created, but never used (#1217)

* DOCS-15357 Count how many pooled connections are created, but never used

* external review feedback

* Update source/reference/command/connPoolStats.txt

Co-authored-by: Réo Kimura <[email protected]>

Co-authored-by: Réo Kimura <[email protected]>

Author: jmd-mongo

source/reference/command/connPoolStats.txt

@@ -338,6 +338,13 @@ Output
    members of the :term:`sharded cluster` or :term:`replica set` that
    are currently being refreshed.
 
+.. data:: connPoolStats.totalWasNeverUsed
+
+   Reports the total number of outgoing connections from the
+   current :binary:`~bin.mongod`/:binary:`~bin.mongos` instance to other
+   members of the :term:`sharded cluster` or :term:`replica set` that
+   were closed having never been used.
+
 .. data:: connPoolStats.replicaSetMatchingStrategy
 
    .. versionadded:: 5.0 (*Also available starting in 4.4.5 and 4.2.13*)
@@ -455,6 +462,11 @@ Output
 
       Displays the DBClient-based pool statistics.
 
+   .. data:: connPoolStats.pools.[pool].poolWasNeverUsed
+
+      Displays the number of connections in this connection pool
+      that were closed having never been used.
+
 .. data:: connPoolStats.hosts
 
    Reports on connection statistics (in
@@ -478,6 +490,12 @@ Output
       Reports the number of connections to the ``[host]``
       that are currently in use.
 
+   .. data:: connPoolStats.hosts.[host].wasNeverUsed
+    
+      Reports the total number of outgoing connections from ``host`` to 
+      other members of the :term:`sharded cluster` or 
+      :term:`replica set` that were closed having never been used.
+
 .. data:: connPoolStats.replicaSets
 
    Contains :term:`documents <document>` that represent a report of