Incorrect description of "Extended Keys" registers $B0 and $B1

[ped7g]

There was typo/leftover in wiki probably from WIP versions of the feature (core 3.1.4), when 0 was pressed and 1 was released.

After the feature was finalised for core3.1.5, the logic was flipped and 0 is released, 1 is pressed (wiki was fixed just recently, nextreg.txt has this change for 2+ years).

https://gitlab.com/SpectrumNext/ZX_Spectrum_Next_FPGA/-/blob/master/cores/zxnext/nextreg.txt#L923

[tomaz]

Thanks, will fix it when I get around!