Update README.md

README.md

@@ -34,7 +34,7 @@ You can also join *git* slack channel on [SoM IRT Slack channel #svn_git_discuss
 ## <a name="422-error" ></a> Why do I get "422 Error" when sign-in?
 
 If you get this error the first time your sign-in, most likely, your email contact information in [StanfordYou](https://stanfordyou.stanford.edu/)
-is either private or doesn't exist. It can be caused by sponsorship changes.
+is either private or doesn't exist. It can be caused by sponsorship changes. The email must be in format of <your sunetid>.stanford.edu.
 
 gitlab.med.stanford.edu service requires your email address to log you in, and the email must be in stanford.edu domain and fully sponsored.
 You should be able to go to stanfordyou.stanford.edu and add your email address -