fixed outdated scaffold instruction in the readme

README.md

@@ -17,7 +17,7 @@ $ brew install micrate
 
 Execute `micrate help` for usage instructions. Micrate will connect to the database specified by the `DATABASE_URL` environment variable.
 
-To create a new migration use the `create` subcommand. For example, `micrate create add_users_table` will create a new SQL migration file with a name such as `db/migrations/20160524162446_add_users_table.sql` that looks like this:
+To create a new migration use the `scaffold` subcommand. For example, `micrate scaffold add_users_table` will create a new SQL migration file with a name such as `db/migrations/20160524162446_add_users_table.sql` that looks like this:
 
 ```sql
 -- +micrate Up