update documentation URL according to configuration at git.kernel.org

* The repositoty path is 'pub/scm/docs/docsko/ieee1394'.
* The CNAME is set to 'ieee1394.docs.kernel.org.'
* Webhook will be configured after this commit, with token generated in
  RTD project setting.

Signed-off-by: Takashi Sakamoto <takaswie@kernel.org>
1 file changed