[mod] make docs-live - remove --port option from sphinx-autobuild

Setting port fixed to 8080 has drawbacks when this port is already in use from
another application [1].  Removing this option from the command line offers the
use of the sphinx-autobuild defaults which are much more flexible [2].

[1] https://github.com/searx/searx/issues/2282
[2] https://github.com/executablebooks/sphinx-autobuild/blob/master/README.md



Signed-off-by: Markus Heiser <markus.heiser@darmarit.de>