Add RELEASING.md with instructions on making a release

Author: rtomayko

RELEASING.md

@@ -0,0 +1,12 @@
+# Making a backup-utils release
+
+ 1. Add a new version and release notes to the `debian/changelog` file.
+ 2. Rev the `share/github-backup-utils/version` file.
+ 3. Tag the release: `git tag v2.0.2`
+ 4. Build that tarball package: `make dist`
+ 5. Install the debian devscripts package if necessary:
+    `sudo apt-get install devscripts`
+ 6. Build the deb package: `debuild -uc -us`
+ 7. Draft a new release at https://github.com/github/backup-utils/releases,
+    including the release notes and attaching the tarball and deb packages.
+ 8. Push the head of the release to the 'stable' branch.