Fixing usage of RAILS_DB to get a rails console for db

Fixing usage of RAILS_DB to get a rails console for db

diff --git a/README.md b/README.md
index 95085bf..f807e96 100644
--- a/README.md
+++ b/README.md
@@ -92,7 +92,7 @@ db_two:
 To get a Rails console that is connected to `some_database_1` database:
 
 `‍``
-RAILS_ENV=db_one rails console
+RAILS_DB=db_one rails console
 `‍``

GitHub sha: c79faa21