Add validation by default

[jodischneider]

Add validation by default.

One easy way to do this would be to add these two lines by default:

• name: cff-validator
  uses: dieghernan/cff-validator@v1

via https://github.com/marketplace/actions/cff-validator

[jspaaks]

Hi Jodi, and welcome to the project! Just to clarify, where would you like to see the validation added?

[jodischneider]

I don't know how to USE the validation - the goal would be to make the validation easier for new CFF users.

[jspaaks]

OK, thanks for the clarification. I agree that validation is helpful