[algorithm.syn,bitset.syn,rand.synopsis,valarray.syn] Add \ref for header (#5666)

Author: hewillk

source/algorithms.tex

@@ -616,7 +616,7 @@
 \indexheader{algorithm}%
 
 \begin{codeblock}
-#include <initializer_list>
+#include <initializer_list>     // see \ref{initializer.list.syn}
 
 namespace std {
   namespace ranges {

source/numerics.tex

@@ -1386,7 +1386,7 @@
 \indextext{random number generation!synopsis|(}
 
 \begin{codeblock}
-#include <initializer_list>
+#include <initializer_list>     // see \ref{initializer.list.syn}
 
 namespace std {
   // \ref{rand.req.urng}, uniform random bit generator requirements
@@ -6568,7 +6568,7 @@
 \rSec2[valarray.syn]{Header \tcode{<valarray>} synopsis}
 \indexheader{valarray}%
 \begin{codeblock}
-#include <initializer_list>
+#include <initializer_list>     // see \ref{initializer.list.syn}
 
 namespace std {
   template<class T> class valarray;         // An array of type \tcode{T}

source/utilities.tex

@@ -8523,7 +8523,7 @@
 and manipulating fixed-size sequences of bits.
 
 \begin{codeblock}
-#include <string>
+#include <string>   // see \ref{string.syn}
 #include <iosfwd>   // for \tcode{istream}\iref{istream.syn}, \tcode{ostream}\iref{ostream.syn}, see \ref{iosfwd.syn}
 
 namespace std {