docs: Add a RELEASING.md file

Author: ids1024

RELEASING.md

@@ -0,0 +1,11 @@
+# Releasing
+
+* Make sure all builds and tests are passing on CI.
+* Update version in `Cargo.toml`.
+* Add new release to `debian/changelog`.
+* No change is needed in `windows/keyboard-configurator.wxs` or `macos/Info.plist`
+  - `windows/build.py` and `macos/build.py` populate the version from `Cargo.toml`
+  - `UpgradeCode` should **not** be changed between releases.
+* Create a release on Github
+  - Github Actions will automatically build artifacts in release mode, and attach them to the release.
+* Deploy release to Pop!\_OS repos.