Removed: link to broken RSS feed

It has been removed from one place previously:
d55d770

This changes only `en`: `ko` and `zh` will be separate patches.

Signed-off-by: Agam Dua <agam_dua@apple.com>

content/en/docs/reference/issues-security/security.md

@@ -19,8 +19,6 @@ This page describes Kubernetes security and disclosure information.
 
 Join the [kubernetes-security-announce](https://groups.google.com/forum/#!forum/kubernetes-security-announce) group for emails about security and major API announcements.
 
-You can also subscribe to an RSS feed of the above using [this link](https://groups.google.com/forum/feed/kubernetes-security-announce/msgs/rss_v2_0.xml?num=50).
-
 ## Report a Vulnerability
 
 We're extremely grateful for security researchers and users that report vulnerabilities to the Kubernetes Open Source Community. All reports are thoroughly investigated by a set of community volunteers.