CWG2640 Allow more characters in an n-char sequence

Fixes NB US 028 (C++23 CD).

Author: burblebee

source/lex.tex

@@ -314,10 +314,7 @@
 
 \begin{bnf}
 \nontermdef{n-char} \textnormal{one of}\br
-    \terminal{A B C D E F G H I J K L M N O P Q R S T U V W X Y Z}\br
-    \terminal{0 1 2 3 4 5 6 7 8 9}\br
-    \textnormal{\unicode{002d}{hyphen-minus}}\br
-    \textnormal{\unicode{0020}{space}}
+     \textnormal{any member of the translation character set except the \unicode{007d}{right curly bracket} or new-line character}
 \end{bnf}
 
 \begin{bnf}