note --no-install-recommends for debian

See #141

Author: jcupitt

README.md

@@ -25,9 +25,11 @@ package managers, homebrew and MacPorts, and there are Windows binaries on
 the vips website. For example, on Debian:
 
 ```
-sudo apt-get install libvips-dev
+sudo apt-get install --no-install-recommends libvips42
 ```
 
+(`--no-install-recommends` stops Debian installing a *lot* of extra packages)
+
 Or macOS:
 
 ```