Tagging process streamlined

A tagRelease.bash script is created in order to streamline the tagging
process. Now tag messages contain a link to the changelog between
versions.

Change-Id: I14effc4e7586f5d41e5c1df5561350fbe5dc48b7
diff --git a/README.md b/README.md
index c3bf730..ca81554 100644
--- a/README.md
+++ b/README.md
@@ -10,9 +10,8 @@
 
 1. Tag the last commit with a version number (in the format `vx`, where x is the
 extension's [version number](https://developer.chrome.com/extensions/manifest/version)
-for that release) by running `git tag -a vx -m "vx"`. Note that the tag should
-be an annotated tag and not a lightweight tag, and it must be pushed to Gerrit
-after being created.
+for that release) by running `bash tagRelease.bash --version vx`. Note that the
+tag must be pushed to Gerrit after being created.
 2. Build the extension for both the stable and beta channels (this is explained
 in the next section). This will output a ZIP file for each release channel and
 each supported browser.