Adding verison to upgrade notice

readme.txt

@@ -170,6 +170,7 @@ Yes, the plugin allows for all settings to be controlled via constants in `wp-co
 3. Assign users into WordPress roles based on arbitrary data provided by Shibboleth
 
 == Upgrade Notice ==
+= 2.0 =
 This update brings with it a major change to the way Shibboleth attributes are accessed. For most users, no additional configuration will be necessary. If you are using a specialized server configuration, such as a Shibboleth Service Provider on a reverse proxy or a server configuration that results in environment variables being sent with the prefix REDIRECT_, you should see the changelog for additional details: https://wordpress.org/plugins/shibboleth/#developers
 
 == Changelog ==
@@ -248,4 +249,4 @@ The Shibboleth plugin is now being maintained by [michaelryanmcneill](https://pr
  - lots of code cleanup and documentation
 
 = version 0.1 =
- - initial public release
+ - initial public release