package/kf5: 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/kf5/Config.in

@@ -6,6 +6,8 @@ menuconfig BR2_PACKAGE_KF5
 	  This option enables the KF5 KDE Frameworks. Sub-options
 	  allow to select which modules should be built.
 
+	  https://techbase.kde.org/KDE_Frameworks
+
 if BR2_PACKAGE_KF5
 source "package/kf5/kf5-extra-cmake-modules/Config.in"
 source "package/kf5/kf5-kcoreaddons/Config.in"