[mythtv] Problem with DataDirect Migration docs

[Chris Petersen]

I'm not sure if this was clear in the docs (if it's there, I missed it
when I was upgrading last night), but you need to run mythfilldatabase
before doing the channel icon stuff.  I know that mythtvsetup tells you
to run mythfilldatabase, but I don't always read "exit" text from
commandline programs, so it might be a good note to add.

Also might be nice to put a dialog box into mythtvsetup that would pop
up after you configure the appropriate sections.

-Chris