Update the readme Quickstart with more details

I also had to do this before creating the db, but I'm not sure if it's just my set up:
```psql postgres

CREATE ROLE "postgres-user" WITH LOGIN PASSWORD 'postgres-password';
ALTER ROLE "postgres-user" CREATEDB;```

README.md

@@ -14,9 +14,15 @@ Pre-requisites
 
 Copy the `.env.example` to `.env` and replace the database credentials with your local postgres user credentials.
 
+Install the dependencies
+`bundle install`
+
 Create the database
 `rake db:create`
 
+Run the database migrations
+`rake db:migrate`
+
 Start the rails server
 ```
 rails s