vips: added info on optional dependencies

diff --git a/vips/README b/vips/README
index 978674fba7c7e9c4e4c6fb98e326fcbca5a98389..cd2527620ed6498a490fd63d8223a2e71ed20abc 100644 (file)
--- a/vips/README
+++ b/vips/README
@@ -15,3 +15,6 @@ letting it work with formats like DICOM.
 It comes with bindings for C, C++, and the command-line.
 
 To build HTML documentation use DOCS=yes. This requires gi-docgen.
+
+Optional dependencies are (autodetected): libspng, highway, matio,
+libjxl and libheif.