api-ref: Fix a broken link

natsumetakashi · natsumetakashi · commit e75598be31d8 · 2019-07-05T13:24:18.000+09:00
The link to the API extension document has been broken.
The API extension document does not exist currently,
so just remove the link.

Change-Id: I8920a00004528f5fa30d1b5a2f53ffa5f65f2ea8
diff --git a/api-ref/source/extensions.inc b/api-ref/source/extensions.inc
@@ -19,9 +19,6 @@ code to interact with every cloud.
 As such, the entire extensions concept is deprecated, and will be
 removed in the near future.
 
-For information about extensions, see `Extensions
-<http://developer.openstack.org/api-guide/compute/extensions.html>`__.
-
 List Extensions
 ===============
 
