intro-quick: replace http:// with ssh:// in fetch example
intro-quick: replace http:// with ssh:// in fetch example

All the other example commands use ssh, so using ssh in this command
makes it consistent. Also, the http command was using the `/p/` URL
infix which is no longer needed.

Change-Id: Ie9ffb50fc5f565f1d7f293dcae106fb285d6553d

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