[strings] Add page breaks.

Partially addresses #4228.

source/strings.tex

@@ -786,6 +786,7 @@
   template<class charT, class traits = char_traits<charT>,
            class Allocator = allocator<charT>>
   class basic_string {
+@\newpage@
   public:
     // types
     using traits_type            = traits;
@@ -1328,6 +1329,8 @@
 The second form throws nothing if \tcode{alloc == str.get_allocator()}.
 \end{itemdescr}
 
+\newpage
+
 \begin{itemdecl}
 template<class InputIterator,
          class Allocator = allocator<typename iterator_traits<InputIterator>::value_type>>
@@ -3683,6 +3686,8 @@
 for the return type.
 \end{itemdescr}
 
+\newpage
+
 \indexlibraryglobal{stof}%
 \indexlibraryglobal{stod}%
 \indexlibraryglobal{stold}%
@@ -4945,6 +4950,9 @@
 \tcode{t <=> sv} & \tcode{S(t) <=> sv} \\
 \tcode{sv <=> t} & \tcode{sv <=> S(t)} \\
 \end{libtab2}
+
+\newpage
+
 \begin{example}
 A sample conforming implementation for \tcode{operator==} would be:
 \begin{codeblock}