Add documentation examples for unexpected-special-method-signature (#7072)

Co-authored-by: Vladyslav Krylasov <vladyslav.krylasov@gmail.com>
Co-authored-by: Pierre Sassoulas <pierre.sassoulas@gmail.com>

Author: 3 people

doc/data/messages/u/unexpected-special-method-signature/bad.py

@@ -0,0 +1,6 @@
+class ContextManager:
+    def __enter__(self, context):  # [unexpected-special-method-signature]
+        pass
+
+    def __exit__(self, type):  # [unexpected-special-method-signature]
+        pass

doc/data/messages/u/unexpected-special-method-signature/details.rst

@@ -1 +1,6 @@
-# This is a placeholder for correct code for this message.
+class ContextManager:
+    def __enter__(self):
+        pass
+
+    def __exit__(self, type, value, traceback):
+        pass