[allocator.requirements.general] Remove redundant template syntax (#5872)

Author: AlisdairM

source/lib-intro.tex

@@ -2234,7 +2234,7 @@
 \end{itemdescr}
 
 \begin{itemdecl}
-typename X::template rebind<U>::other
+typename X::rebind<U>::other
 \end{itemdecl}
 
 \begin{itemdescr}