Update readme with instructions for git-review plugin

Change-Id: I3360691f16a84e323d3cb893f2e83a14104479cf

README.markdown

@@ -16,5 +16,15 @@ always be labeled as EXPERIMENTAL
 
 # Adding or updating a device
 
+This repository is preconfigured to use the git-review plugin. More information can be found at:
+https://pypi.python.org/pypi/git-review
+
 Edit cm-build-targets and submit a change to gerrit for review. The
-syntax for that file is documented in its first few lines
+syntax for that file is documented in its first few lines.
+You can upload your change to gerrit with commands like these:
+
+    git add cm-build-targets
+    git commit
+    git review
+
+Once you have submitted your change add the group "Release" to the reviewers.