Add how to release

Author: backpaper0

how-to-release.md

@@ -0,0 +1,95 @@
+# How to release
+
+## Create release branch
+
+Switch to a new branch to work on the release.
+
+```
+git switch -c release-x.y.z
+```
+
+## Update README
+
+Update the version described in the README.
+
+The following example shows the command to update the description from 1.3.0 to 1.4.0.
+
+```
+sed -i '' -e 's/1\.3\.0/1\.4\.0/g' README.md
+```
+
+## Set a new version
+
+Update pom.xml by Maven Versions Plugin.
+
+```
+./mvnw versions:set -DnewVersion=x.y.z
+```
+
+Run all tests.
+
+```
+./mvnw test
+```
+
+Commit the new version.
+
+```
+./mvnw versions:commit
+```
+
+## Push changes to GitHub
+
+Do `git commit` changes to the README and pom.xml.
+
+```
+git add .
+git commit -m "Release x.y.z"
+```
+
+And do `git push` to GitHub.
+
+```
+git push origin release-x.y.z
+```
+
+## Do release work on GitHub
+
+Create a new PR from release branch and merge it into the master branch.
+
+The CI job running after the merge releases a new version artifact to the Maven Central Repository.
+
+Check https://repo.maven.apache.org/maven2/org/seasar/doma/boot/doma-spring-boot/ .
+
+## Prepare a next SNAPSHOT version
+
+First, pull the master branch.
+
+```
+git switch master
+git pull
+```
+
+Create a new branch.
+
+```
+git switch -c prepare-next-snapshot-version
+```
+
+Set a next SNAPSHOT version to pom.xml and commit.
+
+```
+./mvnw versions:set -DnewVersion=x.z.z-SNAPSHOT
+./mvnw versions:commit
+```
+
+Do `git commit` and push to GitHub.
+
+```
+git add .
+git commit -m "Prepare a next SNAPSHOT version"
+git push origin master
+```
+
+Finally, create a new PR and merge it into the master branch.
+