release: add RELEASE.md with guidelines for new Reps releases

RELEASE.md

@@ -0,0 +1,30 @@
+How to create a new Reps release for mozilla-central.
+Before you get started, you will need clones of devtools-reps and mozilla-central, as well as
+a Bugzilla account.
+
+1. Go to your clone of devtools-reps
+  a. create a release branch on github
+  b. update minor version in package.json, reset build version: 
+    v0.N.X -> v0.N+1.0
+  c. create a PR on Github for this release
+  d. run /bin/publish-assets.js to create the bundle
+
+2. Go to your clone of mozilla-central
+  a. update mozilla-central to the latest
+  b. copy : 
+       assets/build/reps.js      -> devtools/shared/components/reps
+       assets/build/reps.css     -> devtools/shared/components/reps
+       assets/build/load-reps.js -> devtools/shared/components/reps
+       assets/build/mochitest/*  -> devtools/shared/components/reps/test/mochitest/
+  c. commit 'Bug XXXXXXX - reps v0.N+1.0: update devtools reps bundle from GitHub;r=reviewer'
+  d. push to try, test locally, submit for review etc ...
+  e. while try fails or some problem is detected, go back to devtools-reps, fix the issue, 
+     create a new bundle and go back to 2.a
+  f. when everything is fine and the patch is r+, land on autoland or inbound
+  g. merge the PR on github
+  h. create a tag on github
+
+After that any issue with the bundle should be addressed with a new build version. 
+Ideally, if the bundle has to be updated in mozilla-central for a bugfix, a corresponding
+tag should be created on GitHub.
+