documentation: fb: update list of available compiled-in fonts

Update list of available compiled-in fonts in lib/fonts/:
add 6x10 and drop RomanLarge (which was reverted 12 years ago).

Also sort the list alphabetically.

Signed-off-by: Randy Dunlap <rdunlap@infradead.org>
Acked-by: Geert Uytterhoeven <geert@linux-m68k.org> # v1
Signed-off-by: Jonathan Corbet <corbet@lwn.net>