[utilities] Add missing charconv entry to summary table

Author: tkoeppe

source/utilities.tex

@@ -28,7 +28,8 @@
 \ref{time}                  & Time utilities                    & \tcode{<chrono>}      \\
                             &                                   & \tcode{<ctime>}       \\ \rowsep
 \ref{type.index}            & Type indexes                      & \tcode{<typeindex>}   \\ \rowsep
-\ref{execpol}               & Execution policies                & \tcode{<execution>}   \\
+\ref{execpol}               & Execution policies                & \tcode{<execution>}   \\ \rowsep
+\ref{charconv}              & Primitive numeric conversions     & \tcode{<charconv>}    \\
 \end{libsumtab}
 
 \rSec1[utility]{Utility components}