[cpp.stringize] Break one large paragraph into smaller, more readable, ones

Author: AlisdairM

source/preprocessor.tex

@@ -1784,6 +1784,8 @@
 both are replaced by a single character string literal preprocessing token that
 contains the spelling of the preprocessing token sequence for the
 corresponding argument (excluding placemarker tokens).
+
+\pnum
 Let the \defn{stringizing argument} be the preprocessing token sequence
 for the corresponding argument with placemarker tokens removed.
 Each occurrence of whitespace between the stringizing argument's preprocessing
@@ -1801,9 +1803,14 @@
 \unicode{005c}{reverse solidus} character,
 and each new-line character is
 replaced by the two-character sequence \tcode{\textbackslash n}.
+The character string literal corresponding to an empty stringizing argument
+is \tcode{""}.
+
+\pnum
 If the replacement that results is not a valid character string literal,
-the program is ill-formed. The character string literal corresponding to
-an empty stringizing argument is \tcode{""}.
+the program is ill-formed.
+
+\pnum
 The order of evaluation of
 \tcode{\#}
 and