update release notes

Signed-off-by: Harshit Gangal <[email protected]>

changelog/22.0/22.0.0/summary.md

@@ -8,6 +8,8 @@
   - **[RPC Changes](#rpc-changes)**
   - **[Prefer not promoting a replica that is currently taking a backup](#reparents-prefer-not-backing-up)**
   - **[VTOrc Config File Changes](#vtorc-config-file-changes)**
+- **[Minor Changes](#minor-changes)**
+  - **[VTTablet Flags](#flags-vttablet)**
 
 
 ## <a id="major-changes"/>Major Changes</a>
@@ -56,3 +58,12 @@ The following fields can be dynamically changed -
 13. `change-tablets-with-errant-gtid-to-drained`
 
 To upgrade to the newer version of the configuration file, first switch to using the flags in your current deployment before upgrading. Then you can switch to using the configuration file in the newer release.
+
+
+## <a id="minor-changes"/>Minor Changes</a>
+
+#### <a id="flags-vttablet"/>VTTablet Flags</a>
+
+- `twopc_abandon_age` flag now supports values in the time.Duration format (e.g., 1s, 2m, 1h). 
+While the flag will continue to accept float values (interpreted as seconds) for backward compatibility, 
+**float inputs are deprecated** and will be removed in a future release.