[tuple.cnstr] Fix bad escaping in codeblock (#5501)

Author: JohelEGP

source/utilities.tex

@@ -1689,7 +1689,7 @@
 \end{codeblock}
 This constructor is defined as deleted if
 \begin{codeblock}
-(reference_constructs_from_temporary_v<Types, UTypes\&\&> || ...)
+(reference_constructs_from_temporary_v<Types, UTypes&&> || ...)
 \end{codeblock}
 is \tcode{true}.
 \end{itemdescr}