Add RELEASE doc

RELEASE.md

@@ -0,0 +1,31 @@
+# Release checklist
+
+  1. Update CHANGELOG.md with a bulletpoint list of new features and bug fixes.
+  2. Remove the `-dev` from the version numbers in `CHANGELOG.md` and `VERSION`. If
+     doing an `rc` release, mark them appropriately.
+  3. For a non-rc releases, update the version numbers in `README.md`. They
+     won't work until ci.nerves-project.org completes and uploads the systems, but "that's ok".
+  4. Check that the dependencies in the `mix.exs` point to real releases. Mainly
+     check that the `nerves_system_br` dep is correct.
+  5. Run `mix deps.get` to make sure any updates are reflected in the `mix.lock`
+     file.
+  6. Commit changes (this is still in the `develop` branch)
+  7. `git checkout master` and `git pull` just in case `master` isn't up to
+     date.
+  8. `git merge --ff-only develop`
+  9. `git tag -a v<version number>`
+  10. Push latest commit(s) from master *and* the tag to GitHub
+  11. Wait for ci.nerves-project.org to finish building release
+  12. Copy the latest CHANGELOG.md entry to the GitHub releases description.
+      Make sure that the system artifacts are there. If everything is ok,
+      publish the release.
+  13. Run `mix hex.publish package`
+  14. Update and build `blinky` to verify that the new system downloads and
+      builds properly.
+  15. `git checkout develop` (If any changes were made to `master`, fast forward
+      develop to the tip of `master`)
+  16. Start the next dev cycle. Start a new section in `CHANGELOG.md` and
+      update the version in `VERSION` to a `-dev` version.
+  17. Commit version updates to the `develop` branch
+  18. Push changes up to GitHub
+