[meta.reflection.extract] Fix mistaken "C" that should be "X C::*".

This seems to have been a mistake during application of P2996R13.

Author: tkoeppe

source/meta.tex

@@ -5898,8 +5898,8 @@
   \tcode{r} represents a non-static data member with type $X$,
   that is not a bit-field,
   that is a direct member of class \tcode{C},
-  \tcode{T} and \tcode{C} are similar types\iref{conv.qual}, and
-  \tcode{T} is \tcode{is_convertible_v<\brk{}X C::*, T>} is \tcode{true};
+  \tcode{T} and \tcode{X C::*} are similar types\iref{conv.qual}, and
+  \tcode{T} is \tcode{is_convertible_v<X C::*, T>} is \tcode{true};
 \item
   \tcode{r} represents an implicit object member function
   with type \tcode{F} or \tcode{F noexcept}