Fix license link in README.md (#5859)
Fix license link in README.md (#5859)

Noticed GitHub was 404ing when clicking on license links. File used to be LICENSE and it recently changed to LICENSE.md.
Jawshy/twofactorauth,jdavis/twofactorauth,jdavis/twofactorauth,Jawshy/twofactorauth,jdavis/twofactorauth,Jawshy/twofactorauth,Jawshy/twofactorauth