whitequark
Add notes on product terms to Functional outline
When I was experimenting with low-level generation of fusemaps a few months ago, it wasn't immediately obvious to me how product term fuses should be set. In particular, whether 0 is used to enable or disable that signal, and the behavior when all of a product term's fuses are either 0 or 1. I took some notes after figuring it out with some trial-and-error tests on an ATF1502ASV, and happened to stumble on those notes today so I figured I'd clean them up a bit and open a PR in case you want to put it in the docs.
I'm not sure if this is the type of thing you intended for the Functional outline page, and it's a little funny to not have anything else there, but it didn't seem to fit well on the macrocell options pages. If you think this would be better somewhere else or just don't like it at all, feel free to do whatever you want with it.
Not quite what I intended. Let's keep this PR open until this info is properly recorded somewhere; no harm in having it around.
