hwmon: (dell-smm) Update Documentation regarding firmware bugs

When adding the Inspiron 3505 to the fan type blacklist,
the Documentation was not updated to mention the firmware
bug on this machine.
Fix that.

Fixes: 6ba463ed (hwmon: (dell-smm) Add Inspiron 3505 to fan type blacklist)
Signed-off-by: Armin Wolf <W_Armin@gmx.de>
Link: https://lore.kernel.org/r/20220424154824.9396-1-W_Armin@gmx.de


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