Changelog: cleanup 3.6 changelog to remove all bug fixes
Changelog: cleanup 3.6 changelog to remove all bug fixes

The rules should be:
1. Each patch release should only include change against previous
   patch, such as 3.5.4 vs 3.5.5.
2. For the first release (e.g. 3.6.0) for each minor version, we
   should only describe new features or changes which are not
   included in any releases in previous minor version.

Signed-off-by: Benjamin Wang <a1713d12b1b05630690f22cadfd282d625d8acb2@vmware.com>

ajityagaty/etcd,ajityagaty/etcd,etcd-io/etcd,ajityagaty/etcd,etcd-io/etcd,etcd-io/etcd