Removing old networking.md
Updating dockernetworks.md with images
Adding information on network plugins
Adding blurb about links to docker networking
Updating the working documentation
Adding Overlay Getting Started
Downplaying links by removing refs/examples, adding refs/examples for network.
Updating getting started to reflect networks not links
Pulling out old network material
Updating per discussion with Madhu to add Default docs section
Updating with bridge default
Fix bad merge
Updating with new cluster-advertise behavior
Update working and NetworkSettings examples
Correcting example for default bridge discovery behavior
Entering comments
Fixing broken Markdown Syntax
Updating with comments
Updating all the links
Signed-off-by: Mary Anthony <mary@docker.com>