Merge pull request #609 from kobotoolbox/add-shared-database-note-to-…

…readme

Add note about shared-database branch to README

README.md

@@ -4,6 +4,8 @@
 
 Up to and including release [`2.020.18`](https://github.com/kobotoolbox/kobocat/releases/tag/2.020.18), this project (KoBoCAT) and [KPI](https://github.com/kobotoolbox/kpi) both shared a common Postgres database. They now each have their own. **If you are upgrading an existing single-database installation, you must follow [these instructions](https://community.kobotoolbox.org/t/upgrading-to-separate-databases-for-kpi-and-kobocat/7202)** to migrate the KPI tables to a new database and adjust your configuration appropriately.
 
+If you do not want to upgrade at this time, please use the [`shared-database-obsolete`](https://github.com/kobotoolbox/kobocat/tree/shared-database-obsolete) branch instead.
+
 ## Deprecation Notices
 
 Much of the user-facing features of this application are being migrated