Add information about onTag Github Action workflow (#2729)

Author: TimoPtr

docs/android/ci.md

@@ -87,9 +87,13 @@ The [F-Droid](https://f-droid.org) store builds the applications themselves when
 They use the `version_code.txt` file, which is created on every release from the `main` branch, for the app's versioning.
 
 :::warning
-We do not guarantee when the applications will be available on F-Droid after a release. You can find the app [here](https://f-droid.org/packages/io.homeassistant.companion.android.minimal/).
+We do not guarantee when the applications will be available on F-Droid after a release. You can find the app [on F-Droid](https://f-droid.org/packages/io.homeassistant.companion.android.minimal/).
 :::
 
+### On tag
+
+When a tag that matches the [CalVer] versioning format is pushed, the `onTag.yml` workflow is triggered. This workflow generates a new pull request with an updated `changelog_master.xml` file reflecting the new version. Manual approval of this pull request is required. This process helps keep the changelog version aligned with the app version.
+
 ## Summary of workflows
 
 | Workflow         | Trigger                     | Goals                                                                 |
@@ -99,6 +103,7 @@ We do not guarantee when the applications will be available on F-Droid after a r
 | `weekly.yml`     | Every Sunday at 4:00 AM     | Create a pre-release and push the beta build to the Play Store.              |
 | `monthly.yml`    | First day of the month      | Create an initial version tag (`YYYY.MM.0`).                           |
 | `release.yml`    | Manual trigger              | Promote the beta build to production.                                  |
+| `onTag.yml`     | On tag matching [CalVer]         | Update `changelog_master.xml` in a PR.             |
 
 ---