Discuss guest-additions version mismatch.
Discuss guest-additions version mismatch.

This adds a paragraph to the "Start the local cluster" section that
explains the guest-additions mismatch warning and suggests an optional
fix.

Bugs closed: AURORA-1663

Reviewed at https://reviews.apache.org/r/46150/

rdelval/aurora,apache/aurora,rdelval/aurora,apache/aurora,protochron/aurora,apache/aurora,thinker0/aurora,thinker0/aurora,thinker0/aurora,protochron/aurora,crashlytics/aurora,protochron/aurora,medallia/aurora,protochron/aurora,crashlytics/aurora,medallia/aurora,apache/aurora,medallia/aurora,thinker0/aurora,crashlytics/aurora,thinker0/aurora,protochron/aurora,crashlytics/aurora,protochron/aurora,crashlytics/aurora,thinker0/aurora,rdelval/aurora,rdelval/aurora,medallia/aurora,apache/aurora,medallia/aurora,crashlytics/aurora,medallia/aurora,rdelval/aurora,rdelval/aurora,apache/aurora