Doc: update the process of connecting iOS devices

Make one step a note, so that it will not confuse
readers and remove an obsolete step.

Task-number: QTCREATORBUG-10648
Change-Id: I46aa86d8c5c924e367e7bc89682e6726bc0c4eae
Reviewed-by: Robert Loehning <robert.loehning@digia.com>
Reviewed-by: Fawzi Mohamed <fawzi.mohamed@digia.com>
Fix case of "iOS"

Task-number: QTCREATORBUG-10681

Change-Id: I2a51eb95f8f9fa00114a2a9100eec5d052d2cca5
Reviewed-by: Friedemann Kleint <Friedemann.Kleint@digia.com>
Reviewed-by: Fawzi Mohamed <fawzi.mohamed@digia.com>