Propocol release versions properly

On the index page we stopped updating versions table since train. Add
missing entries.

Also small rephrasement in the into on backwards compatibility not to
stick with an ancient release name.
Set oldest release on unreleased page correspondingly.

Change-Id: I4a442708a5b47f573cd2333545531499b9eae0f1

Author: gtema

releasenotes/source/index.rst

@@ -27,14 +27,22 @@ OpenStackClient Release Notes
 OpenStack Releases
 ------------------
 
-OpenStackClient is compatible with all currently supported OpenStack releases,
-it does not require maintaining a 'Mitaka' version to match to a Mitala-release
-cloud.  The OpenStackClient release that was current when the corresponding
-OpenStack release was made is shown below:
+OpenStackClient is intended to be backwards compatible with all currently
+supported OpenStack releases so that it does not require using certain release
+version of the tool to run on a corresponding release version cloud. The
+OpenStackClient release that was current when the corresponding OpenStack
+release was made is shown below:
 
 =================  =======================
 OpenStack Release  OpenStackClient Release
 =================  =======================
+Antelope/2023.1    6.1.0
+Zed                6.0.0
+Yoga               5.7.0
+Xena               5.6.0
+Wallaby            5.5.0
+Victoria           5.3.0
+Ussuri             5.0.0
 Train              4.0.0
 Stein              3.18.0
 Rocky              3.16.0

releasenotes/source/unreleased.rst

@@ -3,4 +3,4 @@ Current Release Notes
 =====================
 
 .. release-notes::
-   :earliest-version: 3.0.0
+   :earliest-version: 6.1.0