Add a RELEASING doc

Author: thockin

RELEASING.md

@@ -0,0 +1,24 @@
+# Cutting a release
+
+```
+$ git tag
+v2.0.0
+v2.0.1
+v2.0.2
+v2.0.3
+v2.0.4
+
+# Pick the next release number
+
+$ git tag -am "v2.0.5" v2.0.5
+
+$ make container TAG=v2.0.5
+<...lots of output...>
+container: gcr.io/google-containers/git-sync-amd64:v2.0.5
+
+$ gcloud docker push -- gcr.io/google-containers/git-sync-amd64:v2.0.5
+<...lots of output...>
+v2.0.5: digest: sha256:904833aedf3f14373e73296240ed44d54aecd4c02367b004452dfeca2465e5bf size: 950
+```
+
+Lastly, make a release through the github UI.