package/qt5quickcontrols2: fix project URL

https://doc.qt.io/qt-5/qtquickcontrols2-index.html is re-directed to
https://doc.qt.io/qt-5/qtquickcontrols-index.html so use it directly

Signed-off-by: Peter Seiderer <ps.report@gmx.net>
Signed-off-by: Arnout Vandecappelle (Essensium/Mind) <arnout@mind.be>
(cherry picked from commit 83bf1790c13a6a6ba4e4008f685d7b824ed15079)
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>

package/qt5/qt5quickcontrols2/Config.in

@@ -12,4 +12,4 @@ config BR2_PACKAGE_QT5QUICKCONTROLS2
 	  This module was in tech preview in Qt 5.6, and promoted
 	  to a core module in Qt 5.7.0.
 
-	  https://doc.qt.io/qt-5/qtquickcontrols2-index.html
+	  https://doc.qt.io/qt-5/qtquickcontrols-index.html