Update release notes with branches

docs/development/release.md

@@ -8,6 +8,20 @@ The kops project is released on an as-needed basis. The process is as follows:
 1. The release issue is closed
 1. An announcement email is sent to `kubernetes-dev@googlegroups.com` with the subject `[ANNOUNCE] kops $VERSION is released`
 
+## Branches
+
+We maintain a `release-1.4` branch for kops 1.4.X, `release-1.5` for kops 1.5.X
+etc.
+
+We create new branches from master as a new kops version is released (or in
+preparation for the release).
+
+Generally we don't encourage users to run older kops versions, or older
+branches, because newer versions of kops should remain compatible with older
+versions of Kubernetes.
+
+Releases should be done from the `release-1.X` branch.  The tags should be made
+on the release branches.
 
 ## Update versions
 
@@ -24,7 +38,7 @@ make ci
 ```
 
 
-## Push new protokube image if needed
+## Push new dns-controller image if needed
 
 ```
 make dns-controller-push DNS_CONTROLLER_TAG=1.5.1 DOCKER_REGISTRY=kope
@@ -39,12 +53,21 @@ make upload S3_BUCKET=s3://kubeupv2
 
 ## Tag new version
 
+Make sure you are on the release branch `git checkout release-1.X`
+
 ```
 export TAG=1.5.0-alpha4
 git tag ${TAG}
 git push --tags
 ```
 
+## Update release branch
+
+For the time being, we are also maintaining a release branch.  We push released
+versions to that.
+
+`git push origin release`
+
 ## Upload to github
 
 Manually create a release on github & upload, but soon we'll publish shipbot which automates this...