Warn about using ssl_context config option (#714)

Update docs added with #639

Co-authored-by: Florent Biville <[email protected]>

Author: robsdedude

docs/source/api.rst

@@ -318,7 +318,12 @@ This setting does not have any effect if ``encrypted`` is set to ``False``.
 ---------------
 Specify a custom SSL context to use for wrapping connections.
 
-If give, ``encrypted`` and ``trusted_certificates`` have no effect.
+If given, ``encrypted`` and ``trusted_certificates`` have no effect.
+
+.. warning::
+    This option may compromise your application's security if used improperly.
+
+    Its usage is strongly discouraged and comes without any guarantees.
 
 :Type: :class:`ssl.SSLContext` or :const:`None`
 :Default: :const:`None`