update release process

DEVELOPERS

@@ -78,11 +78,7 @@ order to make a release has several, easy-to-forget steps.  They are:
      c. Check if nothing has changed and update version and date in
         linux/hydrogen.1
 
-     d. Add new version, date, and ChangeLog to
-	linux/org.hydrogenmusic.Hydrogen.metainfo.xml.in and run
-	`make` in linux/ folder
-
-     e. Update the TARGET_VERSION variable in .appveyor.yml
+     d. Update the TARGET_VERSION variable in .appveyor.yml
 
   2. Run `src/gui/src/about_dialog_contributor_list_update.sh
      GIT_TAG_OF_LAST_RELEASE HEAD` to update the list of recent
@@ -93,53 +89,41 @@ order to make a release has several, easy-to-forget steps.  They are:
 
   4. Commit your changes.
 
-  5. Make a tarball of the release (gzipped).  Use gzip instead of
-     bzip2 for the folks on Windows.  Tarballs should be named:
-
-                   +--- Release version
-                   |
-                   |    +--- Extra release version info
-                 __|__ _|_
-        hydrogen-0.9.4-rc2.tar.gz
-
-     Example: 'tar -pczf hydrogen-0.9.5.tar.gz hydrogen-0.9.5' 
-
-  6. If this is an RC release, the following steps are optional.
-
-  7. In a clean directory, test build the tarball in as many ways as
-     you can.  Call your friends.  Have a party.  Be sure to build
-     packages on as many systems as possible.  Be sure to install
-     and uninstall them, too.
-
-  8. If the release passes these "internal" tests, tag the
-     release.  Remember, after tagging the release you may not
-     commit changes to the tag.
+  5. Create a dedicated branch containing the suffix `-artifacts`,
+     like `releases/1.2.2-release-artifacts`, and manually set in
+     `CMakeLists.txt` the `IS_DEVEL_BUILD` variable to "false" and
+     ensure `DISPLAY_VERSION` does not have a suffix. When pushing
+     this branch to Github, our AppVeyor pipeline will create release
+     artifacts for Linux, macOS, and Windows.
 
-     git tag -a 0.9.4 -m "Tagging 0.9.4"
+  6. Call your friends.  Have a party.  Be sure to tests the artifacts
+     on as many systems as possible.  Be sure to install and uninstall
+     them, too.
 
-  9. Build binary packages in Appveyor for Windows and macOS:
+  7. If the release passes these "internal" tests, add new version,
+     date, ChangeLog as well as the release artifacts including their
+     SHA256 sums to `linux/org.hydrogenmusic.Hydrogen.metainfo.xml.in`
+     and run `make` in `linux/` folder
 
-     - fast-forward merge (or force-push if necessary) releases/XXX to
-       releases/XXX-artifacts, and ensure that the head commit is the
-       one pointed to by the release tag above.
-     - appveyor will build and keep the binary packages as artifacts.
+  8. Tag the release.  Remember, after tagging the release you may not
+     commit changes to the tag.
 
-  10. If this is a major release (e.g. 0.9.4), then make a branch for
-      maintenance patches for your release.  If this is a maintenance
-      release (e.g. 0.9.4.1) then skip this step.
+     git tag -a 0.9.4 -m "Tagging 0.9.4"
+     git push --tags origin
 
-      git branch 0.9.4
-      git push origin 0.9.4
+  9. In case the release is a new major or minor version, also create
+     a dedicated release branch, like `releases/1.2`.
 
-  11. Build a github release, incorporating binary packages, source
+  10. Create a github release, incorporating binary packages, source
       package, tag and release announcement.
 
-  12. Upload the release to SourceForge and make it the default download
+  11. Upload the release to SourceForge and make it the default download
       for all supported platforms.
 
-  13. Make release announcements on
+  12. Make release announcements on
       - [email protected]
       - hydrogen-music.org
 
-  14. Update Homebrew Hydrogen cask:
-      - PR against https://github.com/Homebrew/homebrew-cask/blob/master/Casks/hydrogen.rb
+  13. Update third party repos. Make a PR against:
+      - Homebrew: https://github.com/Homebrew/homebrew-cask/blob/master/Casks/hydrogen.rb
+      - Flatpak: https://github.com/flathub/org.hydrogenmusic.Hydrogen/