Mention MBC30 in MBC3 documentation

[Rangi42]

Pokemon Crystal JP was the only game to use this MBC, which was basically MBC3 but with 8 SRAM banks instead of 4 (and technically allowing 256 ROM banks instead of 128, although Crystal didn't use that). It's mentioned in a footnote on the cartridge header page, but nowhere in the MBC section. More flashcarts are supporting MBC30 (i.e. allowing 8 SRAM banks and 256 ROM banks) as games like Pokemon Coral and Crystal Clear make use of it, so I think this should be documented more clearly.

(from https://redd.it/qvhwi4)

[Rangi42]

Also note that as @pinobatch has pointed out, it may have been "MBC3O":

Is it really MBC30 with a zero or MBC3O with a letter, meaning "MBC3 Oversize"?

If a letter, that would match a pattern on NES where O designates a variant of another cartridge board designed to take a larger memory. This includes UOROM (UNROM + 2 Mbit ROM instead of 1 Mbit) and SOROM (SNROM + two 64 kbit SRAM instead of one).

So far from Google results, people have basically never called it "MBC3O", always "MBC30", despite this evidence. So it may help Pan Docs to mention the "common" name even if it also documents this possible "accurate" name.