[temp.constr.atomic] Split long paragraph into three.

Author: zygoloid

source/templates.tex

@@ -1605,18 +1605,22 @@
 template arguments involving the
 template parameters of the constrained entity,
 called the \defn{parameter mapping}~(\ref{temp.constr.decl}).
+\begin{note}
+Atomic constraints are formed by constraint normalization~(\ref{temp.constr.normal}).
+\tcode{E} is never a logical AND expression~(\ref{expr.log.and})
+nor a logical OR expression~(\ref{expr.log.or}).
+\end{note}
+
+\pnum
 Two atomic constraints are
 \indextext{identical!atomic constraints|see{atomic constraint!identical}}%
 \defnx{identical}{atomic constraint!identical}
 if they are formed from the same
 \grammarterm{expression}
 and the targets of the parameter mappings are equivalent
 according to the rules for expressions described in \ref{temp.over.link}.
-\begin{note}
-Atomic constraints are formed by constraint normalization~(\ref{temp.constr.normal}).
-\tcode{E} is never a logical AND expression~(\ref{expr.log.and})
-nor a logical OR expression~(\ref{expr.log.or}).
-\end{note}
+
+\pnum
 Determining if a constraint is satisfied entails the substitution 
 of the parameter mapping and template arguments into that constraint.
 If substitution results in an invalid type or expression,