docs: hwmon: Include 'inspur-ipsps1.rst' into docs

When generating documentation output Sphinx
outputs a warning for not including
the page 'inspur-ipsps1.rst' in 'index.rst'.

Assuming this documentation is useful it
should be included in the index.

Signed-off-by: Adam Zerella <adam.zerella@gmail.com>
Link: https://lore.kernel.org/r/20190925131715.GB19073@gmail.com


Signed-off-by: Guenter Roeck <linux@roeck-us.net>