Cut-&-paste-o noted by Wolfgang Teschner: decompressobj() returns

*DE*compression objects, not compression objects!

Doc/lib/libzlib.tex

@@ -87,7 +87,7 @@ default size is 16384.
 \end{funcdesc}
 
 \begin{funcdesc}{decompressobj}{\optional{wbits}}
-  Returns a compression object, to be used for decompressing data
+  Returns a decompression object, to be used for decompressing data
   streams that won't fit into memory at once.  The \var{wbits}
   parameter controls the size of the window buffer.
 \end{funcdesc}