Update register name aliases

[Rangi42]

Pan Docs already documents some community register aliases, when the official names were just too obscure:

• P1/JOYP
• AUD* for NRxx ("some alternative names have been proposed, such as AUDENA for NR52")
• BCPS/BGPI
• BCPD/BGPD
• OCPS/OBPI
• OCPD/OBPD

However, there have been some more added in recent hardware.inc versions:

• KEY0/SYS
• KEY1/SPD
• VDMA_* alternatives for HDMA1-5
• SVBK/SMBK/WBK
  • The SMBK ("Select Main ram BanK") alias has existed since rev 3.0 in 2020 ("makes more sense (to me) than rSVBK")
  • The WBK ("Wram BanK") alias has existed since rev 4.10 in 2025 (paralleling the official VBK for "Vram BanK")
  • (Does anyone know what SVBK is even supposed to mean?)

These should be likewise listed in the Pan Docs headings.

(Note that although the proposed rev 5.0 changes many bit number/flag constants, it does not change any register names nor add any aliases.)