Improve documentation

[demeringo]

Problem

Doc is incomplete and Readme is becoming a bit complicated to follow.

Solution

Area to improve

• [x] Building on Linux
• [x] Builing on Windows
• [x] Serverless deployment
• [ ] Methodology (i.e. where data come from) with pointer to Boavizta API material
• [ ] A general page about the different deployments models (CLI vs serverless, and using private API vs other API)
• [ ] A specific chapter about generating metrics (sample rate, data returned)
• [ ] Document setup with prometheus and grafana see #114
• [ ] A chapter about limitations
• [x] It may better work with a dedicated doc, maybe using mdbook https://github.com/rust-lang/mdBook

Alternatives

Additional context or elements

[demeringo]

How to automate publishing mdbook to github pages: https://github.com/rust-lang/mdBook/wiki/Automated-Deployment%3A-GitHub-Pages