Add exception to author Real Name policy

This matches what was decided at the Eclipse Architecture Council in March 2020 which was minuted as follows: A GitHub account as a contributor is ok, it can be traced back to an individual. An ECA must be signed in any case. This requires a real email address and this is sufficient. EMO expectation to committers is to monitor and catch/report shenanigans. The handbook wording needs an updated and will be investigated separately.