[meta.reflection.result] Reorder and reword paragraphs for clarity.

After the "Constant When" => "Throws" reordering, the definition of
the invented variable TCls had moved far from where it was being
referenced. This reordering moves it closer, adds a "defined below",
and moves the example to the end.

Author: tkoeppe

source/meta.tex

@@ -6103,11 +6103,23 @@
 
 \pnum
 \returns
-\tcode{template_arguments_of(\reflexpr{TCls<$V$>})[0]}.
+\tcode{template_arguments_of(\reflexpr{TCls<$V$>})[0]},
+with \tcode{TCls} as defined below.
 \begin{note}
 This is a reflection of an object for class types,
 and a reflection of a value otherwise.
 \end{note}
+
+\pnum
+\throws
+\tcode{meta::exception} unless
+the \grammarterm{template-id} \tcode{TCls<$V$>} would be valid
+given the invented variable
+\begin{codeblock}
+template<T P> struct TCls;
+\end{codeblock}
+
+\pnum
 \begin{example}
 \begin{codeblock}
 template<auto D>
@@ -6129,15 +6141,6 @@
                                                     // points to string literal
 \end{codeblock}
 \end{example}
-
-\pnum
-\throws
-\tcode{meta::exception} unless
-the \grammarterm{template-id} \tcode{TCls<$V$>} would be valid
-given the invented variable
-\begin{codeblock}
-template<T P> struct TCls;
-\end{codeblock}
 \end{itemdescr}
 
 \indexlibraryglobal{reflect_object}%