Added release tagging instructions

RELEASING.TXT

@@ -210,7 +210,17 @@ Note that appengine versions are visible using URLs with this pattern:
 
 http://3-3.schemaorgae.appspot.com/docs/releases.html
 
-5.) Related post-release tasks.
+5.) Tag the code at the current relese state
+* Use a local copy of the relesed version of the 'master' branch:
+    * Either download a new clone, or do a 'git pull' on a local copy and then 'git checkout -b master'
+* Confirm previous tags: 'git tag -l'
+* Tag the local copy eg: 'git tag v3.8-release'
+* Push tagged version to github: 'git push origin v3.8-release'
+Note: If master has moved on from the the released version before tagging
+    * Obtain the last commit identifier before the release from the listing: 'git log master'
+    * Add the commit id to the tag comand. eg: 'git tag v3.8-release 7f86a944e1bd87008cb7b83dc7e19a562ed2d28d'
+
+6.) Related post-release tasks.
 
 * Let the Community Group and Steering Group know.
 * Blog post.