[docs] Update release schedule

It seems that the 6 months between releases is becoming the norm and it
feels comfortable enough.

(cherry picked from commit 3a60ee5)

docs/news/releases.rst

@@ -135,25 +135,27 @@ you can install DebOps in various ways.
 Current release schedule
 ------------------------
 
-- Latest "stable" release: ``stable-2.2`` (`GitHub branch`__, `differences from
+- Latest "stable" release: ``stable-2.3`` (`GitHub branch`__, `differences from
   master`__, `Changelog`__)
 
-.. __: https://github.com/debops/debops/tree/stable-2.2
-.. __: https://github.com/debops/debops/compare/stable-2.2
-.. __: https://docs.debops.org/en/stable-2.2/news/changelog.html
+.. __: https://github.com/debops/debops/tree/stable-2.3
+.. __: https://github.com/debops/debops/compare/stable-2.3
+.. __: https://docs.debops.org/en/stable-2.3/news/changelog.html
 
 =============== ============ =============== ================
  Branch/Tag      Status       First release   End of support
 --------------- ------------ --------------- ----------------
-``stable-4.0``  Planned LTS  2022-01-xx      2028-01-xx
+``stable-4.0``  Planned LTS  2023-06-xx      2028-06-xx
 --------------- ------------ --------------- ----------------
 ...             ...          ...             ...
 --------------- ------------ --------------- ----------------
-``stable-3.2``  Planned      2021-10-xx      2022-10-xx
+``stable-3.2``  Planned      2023-01-xx      2024-01-xx
 --------------- ------------ --------------- ----------------
-``stable-3.1``  Planned      2021-07-xx      2022-07-xx
+``stable-3.1``  Planned      2022-06-xx      2023-06-xx
 --------------- ------------ --------------- ----------------
-``stable-3.0``  Planned      2021-04-xx      2022-04-xx
+``stable-3.0``  Planned      2022-01-xx      2023-01-xx
+--------------- ------------ --------------- ----------------
+``stable-2.3``  Supported    2021-06-04      2022-06-04
 --------------- ------------ --------------- ----------------
 ``stable-2.2``  Supported    2021-01-31      2022-01-31
 --------------- ------------ --------------- ----------------