Use newer suggestion from Hubert

Author: cor3ntin

source/templates.tex

@@ -4595,7 +4595,7 @@
 or \grammarterm{requirement-parameter-list},
 unless that \grammarterm{parameter-declaration} appears in a default argument, or
 \item \grammarterm{parameter-declaration} of a \grammarterm{template-parameter}
-that declares a constant template parameter.
+(which necessarily declares a constant template parameter).
 \end{itemize}
 \end{itemize}
 \begin{example}