[utility] Convert hanging paragraph into [utility.syn] introduction.

For #1771.

Author: zygoloid

source/utilities.tex

@@ -34,14 +34,15 @@
 
 \rSec1[utility]{Utility components}
 
-\pnum
-This subclause contains some basic function and class templates that are used
-throughout the rest of the library.
-
 \indexhdr{utility}%
 \indexlibrary{\idxcode{rel_ops}}%
 \rSec2[utility.syn]{Header \tcode{<utility>} synopsis}
 
+\pnum
+The header \tcode{<utility>}
+contains some basic function and class templates that are used
+throughout the rest of the library.
+
 \begin{codeblock}
 #include <initializer_list>     // see \ref{initializer_list.syn}
 
@@ -177,11 +178,6 @@
 }
 \end{codeblock}
 
-\pnum
-The header \tcode{<utility>} defines several types and function templates
-that are described in this Clause. It also defines the template \tcode{pair}
-and various function templates that operate on \tcode{pair} objects.
-
 \rSec2[utility.swap]{\tcode{swap}}
 
 \indexlibrary{\idxcode{swap}}%