DOCS-13985 clarifies when compound indexes can contain a hashed index field

Author: jmd-mongo

source/core/index-compound.txt

@@ -39,10 +39,22 @@ operation that resembles the following prototype:
 
 .. include:: /includes/fact-index-specification-field-value.rst
 
-.. important:: You may not create compound indexes that have
-   ``hashed`` index type. You will receive an error if you attempt to
-   create a compound index that includes :doc:`a hashed index
-   field </core/index-hashed>`.
+.. important:: 
+
+   Starting in MongoDB 4.4: 
+
+   - Compound indexes may contain **a single** :doc:`hashed index field 
+     </core/index-hashed>`. 
+   - You will receive an error if you attempt to create a compound index 
+     that contains more than one :doc:`hashed index field 
+     </core/index-hashed>`.
+
+   In MongoDB 4.2 or earlier: 
+   
+   - Compound indexes may **not** contain a :doc:`hashed index field 
+     </core/index-hashed>`. 
+   - You will receive an error if you attempt to create a compound index
+     that contains a :doc:`hashed index field </core/index-hashed>`.
 
 Consider a collection named ``products`` that holds documents that
 resemble the following document: