Add documentation for how to create a release

Signed-off-by: Povilas Kanapickas <[email protected]>

RELEASING.md

@@ -0,0 +1,47 @@
+Creating a release
+==================
+
+This file contains instructions for maintainers on how to release new versions of podman-compose.
+
+Step 1: Initialize variables for subsequent steps
+-------------------------------------------------
+
+```
+export VERSION=1.2.3
+```
+
+Step 2: Release notes PR
+------------------------
+
+Open a new branch (e.g. `release`) and run the following:
+
+```
+./scripts/make_release_notes.sh $VERSION
+```
+
+This collects the release notes using the `towncrier` tool and then commits the result.
+This step is done as a PR so that CI can check for spelling errors and similar issues.
+
+Certain file names are not properly supported by the `towncrier` tool and it ignores them.
+Check `newsfragments` directory for any forgotten release notes
+
+Step 3: Merge the release notes PR
+----------------------------------
+
+Step 4: Perform actual release
+------------------------------
+
+Pull the merge commit created on the `main` branch during the step 2.
+Then run:
+
+```
+./scripts/make_release.sh
+```
+
+This will create release commit, tag and push everything.
+
+Step 5: Create a release on Github
+----------------------------------
+
+The release notes must be added manually by drafting a release on the GitHub UI at
+https://github.com/containers/podman-compose/releases.