Added release date

Added release date
Signed off by: Saju<sajmoham@redhat.com>

Author: msaju

docs/release-notes/8.4.md

@@ -1,5 +1,7 @@
 # Release notes for Gluster 8.4
 
+**Release date:** 01-Mar-2021
+
 This is a bugfix release. The release notes for [8.0](8.0.md), [8.1](8.1.md), [8.2](8.2.md) and [8.3](8.3.md)
 contain a listing of all the new features that were added
 and bugs fixed in the GlusterFS 8 stable release.