Update the setup documentation to use correct bin setup command

[jm96441n]

Feature

(Short summary of changes)
Small update to the readme so advise running bin/setup as opposed to bin/setup_test. If it's preferred we could keep the documentation the same and add the bin/setup_test script to handle just setting up the test env.

Checklist

• All existing tests passing

[bensheldon]

Nice catch! Thank you.

I remember I originally named it because I didn't want it to be confused with the Rails script. But looks like I changed the name at and forgot to update the docs.