Add change info to changelog

Signed-off-by: Eduardo J. Ortega U <5791035+ejortegau@users.noreply.github.com>

changelog/22.0/22.0.0/changelog.md

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+# Changelog of Vitess v22.0.0
+
+### Enhancement 
+#### Cluster management
+ * Prefer not promoting replicas that are taking backups [#16997](https://github.com/vitessio/vitess/pull/16997)

changelog/22.0/22.0.0/summary.md

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+## Summary
+
+### Table of Contents
+
+- **[Known Issues](#known-issues)**
+- **[Major Changes](#major-changes)**
+    - **[Support for specifying expected primary in reparents](#reparents-prefer-not-backing-up)**
+
+## <a id="known-issues"/>Known Issues</a>
+
+## <a id="major-changes"/>Major Changes</a>
+
+### <a id="reparents-prefer-not-backing-up"/>Support specifying expected primary in reparents
+
+The execution of both Planned Shard Reparents and Emergency Reparents now prefer promoting replicas that are not
+currently taking backups. Notice that if there's only one suitable replica to promote, and it is taking a backup, it
+will still be promoted.

changelog/22.0/README.md

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+## v22.0
+* **[22.0.0](22.0.0)**
+	* [Changelog](22.0.0/changelog.md)
+	* [Release Notes](22.0.0/release_notes.md)