package/liberation: 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/liberation/Config.in

@@ -5,6 +5,8 @@ config BR2_PACKAGE_LIBERATION
 	  three most commonly used fonts on Microsoft systems:
 	  Times New Roman, Arial, and Courier New.
 
+	  https://github.com/liberationfonts/liberation-fonts
+
 if BR2_PACKAGE_LIBERATION
 
 config BR2_PACKAGE_LIBERATION_MONO