Relaunch Existing Pantheon Site Doc Update

[dficker]

Re: Relaunch Existing Pantheon Site

Priority: High

Issue Description:

At one point in the past, this process included Clearing Caches on both the old site and the new site's live environments. This was apparently for some reason removed, but sporadic Support tickets seem to indicate that is likely still required.

Suggested Resolution

Can we add it back?