[meta.reflection.queries] Use math font consistently

Author: timsong-cpp

source/meta.tex

@@ -4348,7 +4348,7 @@
 
 \pnum
 \returns
-\tcode{true} if \tcode{T} represents a const or volatile type, respectively,
+\tcode{true} if $T$ represents a const or volatile type, respectively,
 or a const- or volatile-qualified function type, respectively.
 Otherwise, \tcode{false}.
 \end{itemdescr}