[range.utility.conv.general] Fix misapplication of LWG4016 (#6932)

Author: cpplearner

source/ranges.tex

@@ -2268,10 +2268,10 @@
 \end{codeblock}
 
 \pnum
-Let \exposid{container-appendable} be defined as follows:
+Let \exposid{container-append} be defined as follows:
 \begin{codeblock}
-template<class Ref, class Container>
-constexpr auto @\exposid{container-appendable}@(Container& c) {                // \expos
+template<class Container>
+constexpr auto @\exposid{container-append}@(Container& c) {                    // \expos
   return [&c]<class Ref>(Ref&& ref) {
     if constexpr (requires { c.emplace_back(declval<Ref>()); })
       c.emplace_back(std::forward<Ref>(ref));