package/mii-diag: add an upstream URL to Config.in

Add an upstream URL to the help text in Config.in. This
addresses the 'Missing' URL status in the package stats
web page output.

Signed-off-by: Mark Corbin <mark@dibsco.co.uk>
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>

package/mii-diag/Config.in

@@ -3,3 +3,5 @@ config BR2_PACKAGE_MII_DIAG
 	help
 	  mii-diag allows you to manipulate the MII registers of
 	  network cards.
+
+	  https://launchpad.net/ubuntu/+source/mii-diag