Update release issue template

.gitlab/issue_templates/release.md

 # Release checklist:
 
-Changes to do on the master branch before releasing:
+## Changes to do on the master branch before releasing
 
-* [ ] update/review `docs/*` and make sure it matches the current state
-  * Update how to checkout the latest stable tag
+Create a MR for the master branch with the following changes:
+
+* update/review `docs/*` and make sure it matches the current state
+  * [ ] Update how to checkout the latest stable tag
+  * [ ] Document how to upgrade in `docs/upgrade.md`
 * [ ] Update dependencies in `requirements-stable.txt`
   1. Create a new `virtualenv` and activate it
   2. Run `pip3 install -r requirements.txt`
@@ -11,23 +14,28 @@ Changes to do on the master branch before releasing:
 * [ ] update [CHANGELOG.md](https://keepachangelog.com/en/1.0.0/)
   * Include `Known issues`
 * [ ] update the version number in the `VERSION` file
-* [ ] commit (signed)
-* [ ] Push to MR, including tag
+  * [ ] commit (signed)
+* [ ] Push to MR
+* [ ] Wait for MR to get merged into master
+
+## Changes to do in the new release branch
+
+* [ ] If this is a major release, create a new release branch (i.e. `v0.5`)
 
-Then, create a release branch, pin deps, and tag the release:
+Create a MR for the new branch with the following changes:
 
-* [ ] If this is a major release, create a new release branch (`v0.4`, etc.).
 * [ ] Ensure all dependencies are updated and locked (locking should be done
     only on the release branch):
   * [ ] chart versions in `flux/*`
   * [ ] in `ansible/group_vars/all/oas.yml`: `flux_source.branch` should be set to the release branch
 * [ ] Make sure the pipeline succeeds for the last commit before tagging. This
       is important because tags should not get retagged !
-* [ ] create signed tag (`git tag -s 0.2.0 -m 'Release 0.2.0'`)
-* [ ] Log into readthedocs.org and update documentation for tagged versions
+* [ ] create and push signed tag (`git tag -s 0.2.0 -m 'Release 0.2.0'`)
+* [ ] Wait for MR to get merged
 
-After release:
+## After release
 
+* [ ] Log into https://readthedocs.org and update documentation for tagged versions
 * [ ] Cherry-pick all changes from the release branch into master which
       shouldn't be only in the 0.4.0 branch (i.e. not the commit locking the
       dependencies)