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'.
This implements the changes required to genreate the pdf version
of the documentation. The pdf will be generated as a build artifact
attached to the build. This is the first patch to enable this
a follow on patch to the website repo will publish the pdf to the
NuttX website.
raiden00pl