Add CodeWithScope deprecation notice to documentation (#216)

Co-authored-by: Nobody <[email protected]>

Author: p-mongo

docs/tutorials/bson-v4.txt

@@ -392,6 +392,13 @@ Represents a string of JavaScript code.
 ``BSON::CodeWithScope``
 ```````````````````````
 
+.. note::
+
+  The ``CodeWithScope`` type is deprecated as of MongoDB 4.2.1. Starting
+  with MongoDB 4.4, support from ``CodeWithScope`` is being removed from
+  various server commands and operators such as ``$where``. Please use
+  other BSON types and operators when working with MongoDB 4.4 and newer.
+
 Represents a string of JavaScript code with a hash of values.
 
 .. code-block:: ruby