Show pip freeze output for all docs jobs

With the 'pip freeze' block at the end of the script, it is not run if
the earlier call to tox to run the doc build fails. Move it up to the
top of the script and run it before the doc build instead.

Change-Id: I7e14ef07599c11babe99f110786a7025d97b1e32
Merge "Show pip freeze output for all docs jobs"