Add script to automate bumping patch versions [ci skip]

Makefile

@@ -0,0 +1,11 @@
+.PHONY: bump guard-%
+
+bump: guard-VERSION
+	$(eval escaped_minor := $(shell echo ${VERSION} | sed -n 's/\([0-9]\+\.[0-9]\+\).*/\1/p' | sed -e 's/[]\/$*.^[]/\\&/g'))
+	sed -i "s/${escaped_minor}\.[0-9]\+/${VERSION}/g" README.md .github/workflows/build-push.yml
+
+guard-%:
+	@ if [ "${${*}}" = "" ]; then \
+		echo "Environment variable $* not set"; \
+		exit 1; \
+	fi

README.md

@@ -96,6 +96,15 @@ For Ruby 3.0, short aliases for latest patch versions are made against Debian 10
 
 Ruby is installed from official APT package repository. Rbenv isn't used.
 
+## Bumping versions
+
+After a new version of Ruby was released:
+
+ 1. Check pull requests at the https://github.com/fullstaq-ruby/server-edition/ repository and ensure that packages for the target version has been build and published (pull request adding this has been merged).
+
+ 2. Execute `make bump VERSION=X.Y.Z` (specify full version in `X.Y.Z`), it will replace previous patch version in both Github Action and README files.
+
+ 3. Commit and push changed `README.md` and `.github/workflows/build-push.yml`. Once they will reach main branch, new images will be pushed to the registry automatically.
 
 [Fullstaq Ruby]: https://fullstaqruby.org/ "Ruby, optimized for production"
 [Hongli Lai]: https://www.joyfulbikeshedding.com/