Docs(nav): fixes obsolete link from left-nav... (#1302)
Docs(nav): fixes obsolete link from left-nav... (#1302)

to new GCE Source to Prod codelab.
spinnaker/spinnaker.github.io,ttomsu/spinnaker.github.io,spinnaker/spinnaker.github.io,spinnaker/spinnaker.github.io,ttomsu/spinnaker.github.io,ttomsu/spinnaker.github.io