Enhance notes for 'b2' libretro core (per Jamiras)

[Hoff16]

Updated notes for the 'b2' libretro core regarding console ID, hashing method, and memory map requirements.

[Hoff16]

FYI this was previously discussed in this Pull Request before the tables re-org of the unsupported page:

#209

[greptile-apps]

Greptile Summary

Updates b2 core notes with missing support requirements.

• Documents console ID, hashing, and memory-map needs.
• Notes that memory is not exposed.

Confidence Score: 5/5

The documentation-only change appears safe to merge.

The updated note matches documented libretro prerequisites and existing terminology.

_{Reviews (1): Last reviewed commit: "Enhance notes for 'b2' libretro core (pe..." | Re-trigger Greptile}