DOCSP-8329 add replanreason to db profiler

Author: andf-mongodb

source/reference/database-profiler.txt

@@ -383,11 +383,21 @@ operation.
 
    .. versionadded:: 3.2.5
 
-   A boolean that indicates whether the query system evicted a cached
-   plan and re-evaluated all candidate plans.
+   A boolean that indicates whether the query system evicted a
+   :ref:`cached plan<query-plans-query-optimization>` and re-evaluated
+   all candidate plans.
 
    Only present when value is ``true``.
 
+.. data:: system.profile.replanReason
+
+   .. versionadded:: 3.6.19
+
+   A string that indicates the specific reason a
+   :ref:`cached plan<query-plans-query-optimization>` was evicted.
+
+   Only present when value for ``replanned`` is ``true``.
+
 .. data:: system.profile.keysInserted
 
    The number of index keys inserted for a given write operation.