PiSmasher Manual is for rev 4.0

[jmerdich]

PSA for folks who are actually doing things with their boards-- the PiSmasher manual is written for version 4.0 of the board. This does not have public schematics (which is honestly fine) and is not labelled in the manual (which is less fine). If you're trying to use the constraints in the manual with the 4.1 rev, you're going to have a bad time.

In particular to my use case, the pins exposed-but-used on the JC1 expansion port differ between the revisions. This isn't a problem, but should be documented and not determined from digging through partial schematics and diffs of example projects after realizing there's a mismatched pin.

I know the piSmasher docs aren't in this repo, but this seems like the best place to file an issue for this. Can we please get the manual labelled as '4.0' and/or get a separate 4.1 revision with the updated pins?