Added a release checklist.

Author: nedtwigg

RELEASE_CHECKLIST.md

@@ -0,0 +1,27 @@
+# Release checklist
+
+- [ ] Update [`CHANGES.md`](CHANGES.md), [`plugin-gradle/CHANGES.md`](plugin-gradle/CHANGES.md), and [`plugin-maven/CHANGES.md`](plugin-maven/CHANGES.md)
+- [ ] Upgrade [`gradle.properties`](gradle.properties).
+- [ ] Run `./gradlew spotlessApply`
+- [ ] Make sure all files are committed
+- [ ] Run `./gradlew check`
+- [ ] Make sure all tests pass and no files are changes
+- [ ] Run :
+
+```
+  ./gradlew generatePomFileForPluginMavenPublication
+  ./gradlew publish publishPlugins
+  ./gradlew publishGhPages
+```
+
+- [ ] Test latest spotless on:
+    - Gradle: https://github.com/junit-team/junit-lambda/blob/151d52ffab07881de71a8396a9620f18072c65ec/build.gradle#L86-L101
+        - `../beam/buildSrc/build.gradle`
+        - `./gradlew spotlessApply`
+    - Maven: https://github.com/jrtom/jung/blob/b3a2461b97bb3ab40acc631e21feef74976489e4/pom.xml#L187-L208
+        - `../jung/pom.xml`
+        - `mvn spotless:apply`
+        - (might take a while for mavencentral to update)
+- [ ] Tag the releases
+- [ ] Bump `gradle.properties` to next snapshot, run `spotlessApply`, commit any changees
+- [ ] Comment on all released PRs / issues