Fix link and description of supported Markdown

Replicates graphql/graphql-js@0c45ddf

Author: Cito

graphql/type/directives.py

@@ -116,8 +116,9 @@ def __repr__(self):
       GraphQLString,
       description='Explains why this element was deprecated,'
                   ' usually also including a suggestion for how to access'
-                  ' supported similar data. Formatted in [Markdown]'
-                  '(https://daringfireball.net/projects/markdown/).',
+                  ' supported similar data.'
+                  ' Formatted using the Markdown syntax, as specified by'
+                  ' [CommonMark](https://commonmark.org/).',
       default_value=DEFAULT_DEPRECATION_REASON)},
   description='Marks an element of a GraphQL schema as no longer supported.')
 

tests/utilities/test_schema_printer.py

@@ -529,8 +529,8 @@ def prints_introspection_schema():
             directive @deprecated(
               """
               Explains why this element was deprecated, usually also including a suggestion
-              for how to access supported similar data. Formatted in
-              [Markdown](https://daringfireball.net/projects/markdown/).
+              for how to access supported similar data. Formatted using the Markdown syntax,
+              as specified by [CommonMark](https://commonmark.org/).
               """
               reason: String = "No longer supported"
             ) on FIELD_DEFINITION | ENUM_VALUE