[uaxid.general] Replace 'C++' with 'this document'

Fixes ISO/CS comment (C++23 proof)

Author: jensmaurer

source/uax31.tex

@@ -6,14 +6,14 @@
 \pnum
 This Annex describes the choices made in application of
 \UAX{31} (``Unicode Identifier and Pattern Syntax'')
-to \Cpp{} in terms of the requirements from \UAX{31} and
-how they do or do not apply to \Cpp{}.
+to this document in terms of the requirements from \UAX{31} and
+how they do or do not apply to this document.
 In terms of \UAX{31},
-\Cpp{} conforms by meeting the requirements
+this document conforms by meeting the requirements
 R1 ``Default Identifiers'' and
 R4 ``Equivalent Normalized Identifiers''.
 The other requirements, also listed below,
-are either alternatives not taken or do not apply to \Cpp{}.
+are either alternatives not taken or do not apply to this document.
 
 \rSec1[uaxid.def]{R1 Default identifiers}