Add user documentation

[atimin]

Is your feature request related to a problem? Please describe.

Currently, the web server has no documentation. There is only one way to figure out how it working. It is configuration files and tests.

Describe the solution you'd like

The web server should have the following documents:

• [x] README with a short description, feature list, installing guide and links to other documentation
• [x] Overview with a structure of the server, descriptions of each element
• [x] Installing with a description of all possible ways to install the server
• [ ] Hello World Example
• [ ] Documentation for:
  • [x] HTTP Server
  • [x] WebSocker Server
  • [ ] WebSocket GateWay