Doc: Add new modules to the "Networking and Connectivity" page

- Qt Serial Port
- Qt Bluetooth
- Qt NFC

Change-Id: Ie031f0e20eb405acd542dbaf9069191f8d421a53
Reviewed-by: Denis Shienkov <denis.shienkov@gmail.com>
Reviewed-by: Laszlo Papp <lpapp@kde.org>
Reviewed-by: Jerome Pasion <jerome.pasion@digia.com>
Reviewed-by: Alex Blasche <alexander.blasche@digia.com>