docs: readlink before copy license file

Instead of a license file there may be a symlink.

features.in/docs/scripts.d/50-docs-license

@@ -1,9 +1,9 @@
-#!/bin/sh
+#!/bin/sh -efu
 # copy distro's licenses into image's rootdir
 
 cd /usr/share/alt-notes || exit 0
 
 find -maxdepth 1 -type f -name "license*.html" -print |
 while read FILE; do
-	cp -av "$FILE" $WORKDIR/
+	cp -av $(readlink -e "$FILE") $WORKDIR/
 done