Paper for minimally changing Annex E to reflect UAX 31 as of Unicode 15.1
for C++26.

Remove R1a Restricted format characters
Remove descriptions of how the standard does not conform with list from
15.1, just state we don't.

I'm leaving them rather than removing them entirely as searching for text
that doesn't exist is difficult.

Implicit change due to Unicode 15 to 15.1 : As of Unicode 15.1, U+200D ZERO
WIDTH JOINER and U+200C ZERO WIDTH NON-JOINER are part of XID_Continue, and
allowed in identifiers.

Dealing with the implications is part of the security profile, and is not
addressed as part of the standard.

https://isocpp.org/files/papers/D3727R0.pdf

Attached are the change-bar paper and the final text for annex E.