[dcl.fct.def.default] Fix misuse of \grammarterm

Author: timsong-cpp

source/declarators.tex

@@ -2112,7 +2112,7 @@
     attribute-specifier-seq\opt decl-specifier-seq\opt declarator virt-specifier-seq\opt{} \terminal{ = default ;}
 \end{ncbnf}
 
-is called an \grammarterm{explicitly-defaulted} definition.
+is called an \term{explicitly-defaulted} definition.
 A function that is explicitly defaulted shall
 
 \begin{itemize}