Update git submodules for Auto

Update git submodules for Auto

Transition to local documentation build for Auto as defined at:

https://docs.opnfv.org/en/latest/how-to-use-docs/local-build-transition.html

Standalone Auto documentation is available at:

https://opnfv-auto.readthedocs.io/en/latest/

This patch adds intersphinx link to the opnfvdocs repo configuration and removes
auto submodule from docs/submodules/

Change-Id: I2e8a57734cd8e5318bbdcffb75876e6890d2f3da
Signed-off-by: Martin Klozik <martin.klozik@tieto.com>