[container.adaptors.general] Fix indentation (#7800)

Author: Andreas-Krug

source/containers.tex

@@ -15562,8 +15562,8 @@
 \item It has both \tcode{KeyContainer} and \tcode{Compare} template parameters, and
 \begin{codeblock}
 is_invocable_v<const Compare&,
-              const typename KeyContainer::value_type&,
-              const typename KeyContainer::value_type&>
+               const typename KeyContainer::value_type&,
+               const typename KeyContainer::value_type&>
 \end{codeblock}
 is not a valid expression or is \tcode{false}.
 \item It has both \tcode{MappedContainer} and \tcode{Allocator} template parameters, and