Bug 1296: restore text describing OptionGroup

Doc/lib/liboptparse.tex

@@ -558,6 +558,39 @@ default value is \code{None}), \code{{\%}default} expands to \code{none}.
 
 \end{itemize}
 
+When dealing with many options, it is convenient to group these
+options for better help output.  An \class{OptionParser} can contain
+several option groups, each of which can contain several options.
+
+Continuing with the parser defined above, adding an
+\class{OptionGroup} to a parser is easy:
+
+\begin{verbatim}
+group = OptionGroup(parser, ``Dangerous Options'',
+                    ``Caution: use these options at your own risk.  ``
+                    ``It is believed that some of them bite.'')
+group.add_option(``-g'', action=''store_true'', help=''Group option.'')
+parser.add_option_group(group)
+\end{verbatim}
+
+This would result in the following help output:
+
+\begin{verbatim}
+usage:  [options] arg1 arg2
+
+options:
+  -h, --help           show this help message and exit
+  -v, --verbose        make lots of noise [default]
+  -q, --quiet          be vewwy quiet (I'm hunting wabbits)
+  -fFILE, --file=FILE  write output to FILE
+  -mMODE, --mode=MODE  interaction mode: one of 'novice', 'intermediate'
+                       [default], 'expert'
+
+  Dangerous Options:
+    Caution: use of these options is at your own risk.  It is believed that
+    some of them bite.
+    -g                 Group option.
+\end{verbatim}
 
 \subsubsection{Printing a version string\label{optparse-printing-version-string}}