docs/library/pyb.rst: Add note about availability of USB MSC-only mode.
@@ -278,7 +278,8 @@ Miscellaneous functions
- ``None``: disables USB
- ``'VCP'``: enable with VCP (Virtual COM Port) interface
- - ``'VCP+MSC'``: enable with VCP and MSC (mass storage device class)
+ - ``'MSC'``: enable with MSC (mass storage device class) interface
+ - ``'VCP+MSC'``: enable with VCP and MSC
- ``'VCP+HID'``: enable with VCP and HID (human interface device)
For backwards compatibility, ``'CDC'`` is understood to mean
