Add errata review to schematic checklist

[jaydcarlson]

I've been burned before by first-rev ICs shipping without functioning crystal oscillators, incorrect peripheral availability on pins, and strange power supply hacks. All of these problems are quietly mentioned in device errata documentation that is often not referenced in the datasheet. These days, before I ship a board out, I always review errata documents for each device, so this item definitely belongs on the checklist!