Add release checklist

docs/release-checklist.md

@@ -0,0 +1,16 @@
+# Release checklist
+
+Version: `1.b.c`
+
+- [ ] Create release branch `releases/v1.b.c`
+  - [ ] Unignore `node_modules/` by adding `!` in front in `.gitignore`
+  - [ ] Delete `node_modules/`
+  - [ ] Install production dependencies: `npm install --production`
+  - [ ] Add `node_modules/`: `git add node_modules`
+  - [ ] Commit & push action: `git commit -a -m "Publish v1.b.c."`, then `git push`
+- [ ] Test the action with an example package
+- [ ] Create tags
+  - [ ] `v1.b.c` pointing at the last commit in `releases/v1.b.c`
+  - [ ] `latest` pointing at the latest version of the highest major version
+  - [ ] `v1` pointing at the latest `1.x.x` version
+- [ ] Push tags