Mention groups and projects indices in documentation of index start command
Mention groups and projects indices in documentation of index start command

Bug: Issue 8629
Change-Id: I61317f6485962069729166b601a109706e71a0a1

GerritCodeReview/gerrit,WANdisco/gerrit,GerritCodeReview/gerrit,WANdisco/gerrit,GerritCodeReview/gerrit,WANdisco/gerrit,qtproject/qtqa-gerrit,WANdisco/gerrit,qtproject/qtqa-gerrit,qtproject/qtqa-gerrit,GerritCodeReview/gerrit,GerritCodeReview/gerrit,WANdisco/gerrit,GerritCodeReview/gerrit,qtproject/qtqa-gerrit,qtproject/qtqa-gerrit,GerritCodeReview/gerrit,WANdisco/gerrit,qtproject/qtqa-gerrit,WANdisco/gerrit,GerritCodeReview/gerrit,qtproject/qtqa-gerrit