Add small doc file describing release workflow

Author: Donien

PUBLISH.md

@@ -0,0 +1,67 @@
+# Creating a new release
+
+> This is meant as an *internal* note on how to build and publish a new version of this Ansible Collection.
+
+1. **Get the release branch ready:**  
+   Push your local changes to the remote.  
+   From your local release branch:  
+   ```
+   git push --set-upstream origin release/<VERSION>
+   ```
+
+   To avoid having leftover files from your local directory end up in the release, please **cleanly clone the release branch to another directory**.  
+   ```
+   git clone --branch release/<VERSION> [email protected]:Icinga/ansible-collection-icinga.git release_<VERSION>
+   cd release_<VERSION>
+   ```
+   You now only have files that were actually commmited.  
+
+2. **Increase the version number:**  
+   The version of this Collection - as seen by Ansible Galaxy - is determined by **galaxy.yml**.  
+   Increase the version number inside accordingly.   
+
+3. **Create a changelog summary:**  
+   This will be shown in the changelog as a short summary for this release.  
+
+   changelogs/fragments/release_summary.yml:  
+   ```
+   release_summary: |
+     Summary text for this release.
+     "*Bugfix release*" for example.
+   ```
+
+4. **Create a new changelog:**  
+   Lint the changelogs:  
+   ```
+   antsibull-changelog lint
+   ```
+
+   Generate the changelog:  
+   ```
+   antsibull-changelog release --version <VERSION>
+   ```
+
+   Commit your changes to the release branch.
+
+5. **Build and push to Ansible Galaxy:**  
+   Build a release tar ball (verbose shows skipped files):  
+   ```
+   ansible-galaxy collection build -vvv
+   ```
+
+   Push to Ansible Galaxy:  
+   ```
+   ansible-galaxy collection publish --token <TOKEN> icinga-icinga-<VERSION>.tar.gz
+   ```
+   > This might show errors which does **not** necessarily mean that it failed.  
+   > Have a look at [Ansible Galaxy](https://galaxy.ansible.com/ui/repo/published/icinga/icinga/) and confirm if the release could be published.
+
+6. **Create a release on GitHub:**  
+   When [creating a new release](https://github.com/Icinga/ansible-collection-icinga/releases/new)  
+
+   - choose \<VERSION\> as tag
+   - choose the branch "release/\<VERSION\>" as target (will be tagged)
+   - choose \<VERSION\> as title
+   - copy and paste the release's changelog entry (see [prior releases](https://github.com/Icinga/ansible-collection-icinga/releases))
+   - attach the created tar ball (icinga-icinga-\<VERSION\>.tar.gz) to the release
+   - if you feel extra nice, credit contributors by adding their names, e.g. behind the respective issue or feature (`@name`)

galaxy.yml

@@ -43,3 +43,4 @@ build_ignore:
   - changelogs
   - .idea
   - '*.tar.gz'
+  - PUBLISH.md