[meta.type.trans] Strike redundant and confusing note on type member of

basic_common_reference, and replace it with a clarifying description of
the primary template.

Author: zygoloid

source/utilities.tex

@@ -16995,12 +16995,8 @@
  \tcode{struct}
  \hspace*{2ex}\tcode{basic_common_reference;}
  &
- A program may specialize this trait (as specified in Note D, below). If there
- is a member \tcode{type}, it shall be a \grammarterm{typedef-name}.
- \begin{note}
- Such specializations can be used to influence the result of
-  \tcode{common_reference}.
- \end{note} \\ \rowsep
+ Unless this trait is specialized (as specified in Note D, below),
+ there shall be no member \tcode{type}. \\ \rowsep
 
 \indexlibrary{\idxcode{common_reference}}%
 \tcode{template<class... T>} \tcode{struct common_reference;}
@@ -17076,7 +17072,7 @@
     \tcode{const volatile short}.
   \end{example}
 \item \tcode{\placeholdernc{COND_RES}(X, Y)} be
-  \tcode{decltype(false ? declval<X(\&)()>()() : declval<Y(\&)()>()())}.
+  \tcode{decltype(false ?\ declval<X(\&)()>()() :\ declval<Y(\&)()>()())}.
 \end{itemize}
 Given types \tcode{A} and \tcode{B},
 let \tcode{X} be \tcode{remove_reference_t<A>},
@@ -17233,7 +17229,9 @@
 \tcode{is_same_v<T, decay_t<T>{>}} and
 \tcode{is_same_v<U, decay_t<U>{>}} are each \tcode{true}.
 \begin{note}
-Such specializations are needed when only explicit conversions are desired
+Such specializations
+can be used to influence the result of \tcode{common_reference}, and
+are needed when only explicit conversions are desired
 between the template arguments.
 \end{note}
 Such a specialization need not have a member named \tcode{type}, but if it does,