Shorten a few section titles.
diff --git a/Doc/lib/libzlib.tex b/Doc/lib/libzlib.tex
index aaf4684..bdee0a0 100644
--- a/Doc/lib/libzlib.tex
+++ b/Doc/lib/libzlib.tex
@@ -2,9 +2,9 @@
% hasn't been updated completely.
\section{\module{zlib} ---
- Compression and decompression compatible with \program{gzip}.}
-\declaremodule{builtin}{zlib}
+ Compression library compatible with \program{gzip}.}
+\declaremodule{builtin}{zlib}
\modulesynopsis{Low-level interface to compression and decompression
routines compatible with \program{gzip}.}