(DOCSP-27076): Clarify version behavior for comparison operators in a $lookup (#2821)

* (DOCSP-27076): Remove eq from list of operators that can use a lookup index in 5.0

* remove version reference

Author: jeff-allen-mongo

source/includes/expr-operators-and-indexes.rst

@@ -1,13 +1,12 @@
-Starting in MongoDB 5.0, the :expression:`$eq`, :expression:`$lt`,
-:expression:`$lte`, :expression:`$gt`, and :expression:`$gte` comparison
-operators placed in an :query:`$expr` operator can use an index on the
-``from`` collection referenced in a :pipeline:`$lookup` stage.
-Limitations:
+The :expression:`$eq`, :expression:`$lt`, :expression:`$lte`,
+:expression:`$gt`, and :expression:`$gte` comparison operators placed in
+an :query:`$expr` operator can use an index on the ``from`` collection
+referenced in a :pipeline:`$lookup` stage. Limitations:
 
 - :ref:`Multikey indexes <index-type-multikey>` are not used.
 
 - Indexes are not used for comparisons where the operand is an array or
   the operand type is undefined.
 
 - Indexes are not used for comparisons with more than one :ref:`field
-  path <agg-quick-ref-field-paths>` operand.
+  path <agg-quick-ref-field-paths>` operand.