(DOCS-14317): Clarification for index filters

Author: jeff-allen-mongo

source/core/query-plans.txt

@@ -232,19 +232,20 @@ The ``queryHash`` and ``planCacheKey`` are available in:
 Index Filters
 -------------
 
-Index filters determine which indexes the optimizer evaluates for a
-:term:`query shape`. A query shape consists of a combination of query,
-sort, and projection specifications. If an index filter exists for a
-given query shape, the optimizer only considers those indexes
-specified in the filter.
+Index filters are set with the :dbcommand:`planCacheSetFilter` command
+and determine which indexes the optimizer evaluates for a :term:`query
+shape`. A query shape consists of a combination of query, sort, and
+projection specifications. If an index filter exists for a given query
+shape, the optimizer only considers those indexes specified in the
+filter.
 
 When an index filter exists for the query shape, MongoDB ignores the
 :method:`~cursor.hint()`. To see whether MongoDB applied an index
 filter for a query shape, check the :data:`~explain.queryPlanner.indexFilterSet`
 field of either the :method:`db.collection.explain()` or the
 :method:`cursor.explain()` method.
 
-Index filters only affects which indexes the optimizer evaluates; the
+Index filters only affect which indexes the optimizer evaluates; the
 optimizer may still select the collection scan as the winning plan for
 a given query shape.
 
@@ -261,4 +262,4 @@ See :dbcommand:`planCacheListFilters`,
 
 .. seealso::
 
-   :doc:`/applications/indexes`
+   :doc:`/applications/indexes`