Breaking and Syncing an MD Root Mirror

Here's one of those times where I thought, "I wonder", as in I wonder if
I can break an MD root mirror and sanely recreate it.  You can do so with
other software RAID solutions so why not here?  Well, you can.  There is
nothing short about this procedure, taking 80+ commands to accomplish.

Creating an MD Root Mirror in Linux

For whatever reason, you originally set up your Linux host without a root
disk mirror and now you want it mirrored.  One could say "just re-install,"
but surely there is another way, and there is.  The solution isn't quick
or simple, though it isn't impossible.  Our host details are: