add references between getopt and optparse docs
diff --git a/Doc/lib/liboptparse.tex b/Doc/lib/liboptparse.tex
index befc361..f2d2d8c 100644
--- a/Doc/lib/liboptparse.tex
+++ b/Doc/lib/liboptparse.tex
@@ -1709,3 +1709,7 @@
 are present after parsing:
 
 \verbatiminput{required_2.py}
+
+\begin{seealso}
+  \seemodule{getopt}{More traditional Unix-style command line option parsing}
+\end{seealso}