[TestNG] Add README.md with usage instructions
[TestNG] Add README.md with usage instructions

(cherry picked from commit d2e4f5c)

paoloambrosio/cucumber-jvm,cucumber/cucumber-jvm,cucumber/cucumber-jvm,cucumber/cucumber-jvm,cucumber/cucumber-jvm,paoloambrosio/cucumber-jvm,cucumber/cucumber-jvm,paoloambrosio/cucumber-jvm,paoloambrosio/cucumber-jvm