sync demo doc and text

Author: vladimir-dudnik

demos/python_demos/text_spotting_demo/text_spotting_demo.py

@@ -84,7 +84,8 @@ def build_argparser():
     args.add_argument('-d', '--device',
                       help='Optional. Specify the target device to infer on, i.e : CPU, GPU. '
                            'The demo will look for a suitable plugin for device specified '
-                           '(by default, it is CPU).',
+                           '(by default, it is CPU). Please refer to OpenVINO documentation '
+                           'for the list of devices supported be the model. ',
                       default='CPU', type=str, metavar='"<device>"')
     args.add_argument('-l', '--cpu_extension',
                       help='Required for CPU custom layers. '