Docs improvement

[DavidMarquezF]

Right now I feel like the docs are lacking a bit. I know this is constant development but I wanted to know if there was any plan in improving mostly the following aspects:

• Getting started guide: 2 - onboard, 3 - interact
• dashboard: example auth_config.json doesn't work (not sure if it should, but gives unknown client error). An explanation on how to set up the auth_config or a description of what each parameter means
• A full example, start to finish on how to set up and use the whole system (maybe even with a device set up from the getting started guide from iotivty, this way it would be a fitting follow-up)
• How plgd compares to other platforms
• Document reference architectures
• Fix C4 diagram and dependencies between GWs and EB

I understand documentation might not be high priority right now but I thought I would create the issue either way.