ignore known warnings:
/home/raiden00/git/RTOS/nuttx/nuttx/Documentation/reference/os/netdev.rst:61: WARNING: Duplicate C declaration, also defined at reference/os/netdev:39.
Declaration is '.. c:struct:: net_driver_s'.
/home/raiden00/git/RTOS/nuttx/nuttx/Documentation/reference/user/07_signals.rst:180: WARNING: Duplicate C declaration, also defined at reference/user/structures:112.
Declaration is '.. c:struct:: sigaction'.
