Explain stash.

doc/update/upgrader.md

 # GitLab Upgrader 
 
-GitLab Upgrader - ruby script that allows you easily upgrade GitLab to latest minor version.
-Ex. it can update your application from 6.4 to latest GitLab 6 version (like 6.5.1).
-You still need to create backup and manually restart GitLab but all other operations can be done by upgrade tool.
+GitLab Upgrader - a ruby script that allows you easily upgrade GitLab to latest minor version.
+For example it can update your application from 6.4 to latest GitLab 6 version (like 6.6.1).
+You still need to create a a backup and manually restart GitLab after runnning the script but all other operations are done by this upgrade script.
+If you have local changes to your GitLab repository the script will stash them and you need to use `git stash pop` after running the script.
 
-__GitLab Upgrader is available only for version 6.4.2 or higher__
+__GitLab Upgrader is available only for GitLab version 6.4.2 or higher__
 
 ### 0. Backup
 
@@ -20,10 +21,9 @@ __GitLab Upgrader is available only for version 6.4.2 or higher__
     cd /home/git/gitlab
     sudo -u git -H ruby script/upgrade.rb
 
-    # it also supports -y option to avouid user input
+    # it also supports -y option to avoid waiting for user input
     # sudo -u git -H ruby script/upgrade.rb -y
 
-
 ### 3. Start application
 
     sudo service gitlab start