Added basic README

README.md

+# OBM-Buildings Database Management
+
+This repository handles the structure and migrations in the `obm_buildings` database.
+
+The database is described through sql files in the `migrations/` directory.
+
+## More information
+
+* [Database versioning best practices](https://enterprisecraftsmanship.com/posts/database-versioning-best-practices/)