Add newline after db create

[ruudk]

When creating a new project, I found that the generated README.md was missing a newline after the buffalo db create -a command.

See:

...
### Create Your Databases

Ok, so you've edited the "database.yml" file and started postgres, now Buffalo can create the databases in that file for you:

	$ buffalo db create -a
## Starting the Application
...

This PR adds an extra newline after the command to make it more pretty!

[markbates]

thanks!