[3.14] Make sure the :keyword: role works for case (pythonGH-138878) (python#139200)

Make sure the ``:keyword:`` role works for ``case`` (pythonGH-138878)
(cherry picked from commit 848d926)

Co-authored-by: sobolevn <[email protected]>

Author: miss-islington

Doc/reference/compound_stmts.rst

@@ -590,6 +590,7 @@ the items are surrounded by parentheses. For example::
       statement.
 
 .. _match:
+.. _case:
 
 The :keyword:`!match` statement
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