Update the content of the website

[aminya]

Atom community has surpassed its initial goal, and the content of the current website is out of date. We should market the organization as an independent community-driven effort, and we need to focus on the many features and packages offered.

The installation procedure has also changed. As of now, the installation of "atom-ide-base" would install everything automatically.

We don't need to mention the old ide-ui package and the history of Nuclide and Facebook. Especially, because in the future versions, we will not allow/recommend simultaneous running of ide-ui due to the conflicts and the bugs it creates for our packages (example).

Other than few minor things, the atomic packages cover all the things ide-ui provides and much more. The license files already cover the "possible" use of code from nuclide.

[bennypowers]

Since much of the site deals with package APIs, we can also offer a "contributing" section, i.e. how to take part in community development. It can document things like

• How (and where) to file bugs
• How to build and run atom locally
• How to contribute to package development
• How to participate in community decision-making
• How to contribute to the docs