wsapi: add LICENSE_FILES

Signed-off-by: Francois Perrad <francois.perrad@gadz.org>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>

package/wsapi/wsapi.mk

@@ -6,5 +6,6 @@
 
 WSAPI_VERSION = 1.6.1-1
 WSAPI_LICENSE = MIT
+WSAPI_LICENSE_FILES = $(WSAPI_SUBDIR)/doc/us/license.html
 
 $(eval $(luarocks-package))