FIXUP CWG2720: Fix missed \grammarterm.

Author: burblebee

source/templates.tex

@@ -4473,7 +4473,7 @@
 immediately following its definition
 would be ill-formed
 due to a construct
-(other than a \tcode{static_assert-declaration} that fails)
+(other than a \grammarterm{static_assert-declaration} that fails)
 that does not depend on a template parameter, or
 \item
 the interpretation of such a construct