Replace URLs for workflow documentation to appropriate parts of the
OpenStack Project Infrastructure Manual.
Also update some outdated/obsolete devstack-related URLs.
Change-Id: I84e3a62b0aec7cb62d10b8b41eac27b15326ab5c
The name of the section "If you're a developer, start here"
has changed in the wiki, now is "If you're a developer".
This commit updates it to correctly refer to the
proper section.
Change-Id: I36c7e868f1c77d9efef0a0eadce9342212423c65