[dcl.attr.contract] Fix typeface of std::terminate in comment.

Author: zygoloid

source/declarations.tex

@@ -4322,7 +4322,7 @@
 void f(int x) noexcept [[expects: x > 0]];
 
 void g() {
-  f(0);                                         // std::terminate() if violation handler throws
+  f(0);                                         // \tcode{std::terminate()} if violation handler throws
   @\commentellip@
 }
 \end{codeblock}