Add .tox to .gitignore
Add .tox to .gitignore

Running tox in docs folder generates .tox as output directory.

Change-Id: Ic8f4ec72771bcc1211e360c791aeffbbb787168d
Signed-off-by: Vishal Thapar <c3b9ed89c5d07264fd87799167335bf2ad91936e@ericsson.com>

opendaylight/netvirt,opendaylight/netvirt,opendaylight/netvirt,opendaylight/netvirt,opendaylight/netvirt