Add description for wave.setcomptype() values
 (backport from rev. 56451)
diff --git a/Doc/lib/libwave.tex b/Doc/lib/libwave.tex
index c0f300b..936bbed 100644
--- a/Doc/lib/libwave.tex
+++ b/Doc/lib/libwave.tex
@@ -142,6 +142,8 @@
 
 \begin{methoddesc}[Wave_write]{setcomptype}{type, name}
 Set the compression type and description.
+At the moment, only compression type \samp{NONE} is supported,
+meaning no compression.
 \end{methoddesc}
 
 \begin{methoddesc}[Wave_write]{setparams}{tuple}