Remove glance image API release note

As per the discussion on the below patch, we haven't agreed on publicizing
the REST API for external consumption.

https://review.openstack.org/#/c/258658/

Change-Id: Ieeafec6d3ca1266f8ec60d978c2e6a562d23d0bc

releasenotes/notes/angularize-images-table-api-eb54206cc9ecc329.yaml

@@ -1,5 +0,0 @@
----
-prelude: >
-    Added new JS REST features for Glance
-features:
-  - Image create/update/delete calls (post/patch/delete)