Added (minimal) StringIO docs.
diff --git a/Doc/lib/lib.tex b/Doc/lib/lib.tex
index a7c86d7..66c6b0c 100644
--- a/Doc/lib/lib.tex
+++ b/Doc/lib/lib.tex
@@ -93,6 +93,7 @@
 \input{libregex}
 \input{libregsub}
 \input{libstruct}
+\input{libstrio}
 \input{libsoundex}
 
 \input{libmisc}			% Miscellaneous Services