Luanti 5.12 compatibility notes

[appgurueu]

Collection of things to be mentioned in the 5.12 compatibility notes:

• scancodes (duh)
• Fix overrideable hand ToolCapabilities and range luanti#15743 (this is a bugfix, but as per usual some content turns out to rely on the bug)
• stricter item registration (see sfan's PRs)
• perlin noise was value noise (e.g. Rename Perlin noise to (fractal) value noise luanti#15858)

[kno10]

Also maybe LBM reliability issues? #15902 #15919

[y5nw]

• scancodes (duh)[x]

Related: #211.