Update README with note re login credentials

[maebeale]

Add note re login credentials in setup section of README.

Below the following:

$ bundle install
$ yarn install
$ rake dev:setup
$ heroku local -f Procfile.dev
# if you chose the local route, then you are good to go on:
  http://localhost:5000
  $ rspec (to run the test suite)
# If you chose the Docker route:
  $ docker-compose up -d -or- $ docker-compose up
  http://localhost:3000
$ rspec (to run the test suite)

Add:

View `seeds.rb` file for login email and password to use while working in development

[mai-am]

I can do this!

[mai-am]

I can do this!

Sorry, I see that maybe someone already did this. I'm new to this so I hope I didn't cause any extra hassle.

[maebeale]

We've been assigning whoever adds the first comment, so best to wait after you add that you'd like to claim an issue. But, no trouble at all! Thanks for jumping in @mai-am !