docs: netlink: link to family documentations from spec info

To increase the chances of people finding the rendered docs
add a link to specs.rst and index.rst.

Add a label in the generated index.rst and while at it adjust
the title a little bit.

Reviewed-by: Breno Leitao <>
Reviewed-by: Donald Hunter <>
Reviewed-by: Jiri Pirko <>
Signed-off-by: Jakub Kicinski <>
3 files changed