Documentation issues

[otroan]

1. The main documentation page is ugly. https://fd.io/documentation/ It's difficult to find the VPP documentation.
2. Where to store documentation? Is it fine to keep it on github? Currently half of the documentation is in VPP repo and some parts on github, and the developer documentation is on nexus.
3. Pointer from documentation to featurelist. Ensure feature list is marked with generation date / version
4. Automatically update documentation for master per patch
5. Automate documentation for release. Currently requires manually updating config.toml, content/documentation/vpp.md, content/vppProject/vppbuilding/vpp.md and vpp/docs/conf.py
6. A google returns lots of very old links, back to 17.04.
7. What about vpp.readthedocs.io?

[ayourtch]

I created #100 for (2), as that item seems to be the most foundational to deal with the first. we can use this issue as a "central documentation meta" to reference all the rest - for the others it makes more sense to have "one issue per issue" so that it is somewhat trackable.