update ref links

Author: yuuuxt

README.md

@@ -7,4 +7,9 @@ add the following extension to postgres.
 https://github.com/tvondra/sequential-uuids
 
 think of migrating data:
+
 https://github.com/tianon/docker-postgres-upgrade/blob/master/README.md
+
+https://medium.com/better-programming/how-to-upgrade-your-postgresql-version-using-docker-d1e81dbbbdf9
+
+https://stackoverflow.com/questions/29600369/starting-and-populating-a-postgres-container-in-docker