It was bidirectional on the Microcontroller sheet, which is wrong.  Now
it's input, like it should be.

0 Ω resistors are cheap, and switches are expensive.  It would be nice
to be able to save the price of a switch, since it's not really
necessary anyway.  I can program these by SWD, after all.

I added a 0 Ω resistor, R11, to pull the BOOT pin to ground in lieu of
having SW1 installed to do the same job.

I had the source and drain reversed—whoops.  After fixing it with an
X-Acto knife and some point-to-point wiring, I've updated the schematic
and PCB files accordingly.

THIS ALSO MARKS THE BEGINNING OF DEVELOPMENT OF THE NEXT BOARD REVISION.

Tested to probably not blow anything up if assembled properly!