Update README.md

Removing language about CLAs and procedures for contributing to the project
Update contributing.md

Removing language about CLAs and procedures for contributing to the project
Merge branch 'develop' of github.com:ozone-development/meridian into documentation/464/fix-grunt-task-for-pubsub-documentation

* 'develop' of github.com:ozone-development/meridian:
  Update contributing.md
  Update README.md