Documentation: fix input related doc refs

Make `input` document refs valid including:
  - joystick
  - joystick-parport

Signed-off-by: Tom Saeger <tom.saeger@oracle.com>
Reviewed-by: Takashi Iwai <tiwai@suse.de>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
4 files changed