[range.slide.iterator] Remove @ in \tcode (#5309)

Author: cpplearner

source/ranges.tex

@@ -12355,7 +12355,7 @@
 \begin{itemdescr}
 \pnum
 \effects
-Equivalent to: \tcode{return views::counted(\exposid{current_} + n, @\exposid{n_}@);}
+Equivalent to: \tcode{return views::counted(\exposid{current_} + n, \exposid{n_});}
 \end{itemdescr}
 
 \begin{itemdecl}