DOCSP-24857 clarify type of operators removed (#1716)

Author: Dave Cuthbert

source/release-notes/6.0-compatibility.txt

@@ -109,7 +109,7 @@ Regular Expressions
 Removed Operators
 -----------------
 
-Starting in MongoDB 5.1, these operators are removed:
+Starting in MongoDB 5.1, these legacy query operators are removed:
 
 .. list-table::
    :header-rows: 1