Greatly expand uninstall procedure

[vinyar]

It would seem there are a few steps/commands missing from the uninstall procedure.
URL: https://docs.chef.io/uninstall.html

(This is not yet a full list, but I don't want to lose sight of it, so here is a partial list so far):

Chef-server - after uninstalling, there might still be some processes remaining like runsvdir:
stop all chef services chef-server-ctl stop
stop manage chef-manage-ctl stop
stop runsvdir initctl stop private-chef-runsvdir


<step for anything else redis/pgres/etc..>