Drop tag assertion from README

The TC is removing the tag framework and has already removed most
of the tags mentioned in the README. This removes the link and
references.

Change-Id: Ia7c95728e3ee4cf7455dc2b7f663d36bb6759fcb

Author: kk7ds

README.rst

@@ -2,23 +2,6 @@
 OpenStack Glance
 ================
 
-.. image:: https://governance.openstack.org/tc/badges/glance.svg
-    :target: https://governance.openstack.org/tc/reference/tags/index.html
-    :alt: The following tags have been asserted for the Glance project:
-          "project:official",
-          "tc:approved-release",
-          "stable:follows-policy",
-          "tc:starter-kit:compute",
-          "vulnerability:managed",
-          "assert:supports-upgrade",
-          "assert:follows-standard-deprecation".
-          Follow the link for an explanation of these tags.
-.. NOTE(rosmaita): the alt text above will have to be updated when
-   additional tags are asserted for Glance.  (The SVG in the
-   governance repo is updated automatically.)
-
-.. Change things from this point on
-
 Glance is an OpenStack project that provides services and associated libraries
 to store, browse, share, distribute and manage bootable disk images,
 other data closely associated with initializing compute resources,