Improve docs with step by step setup

[onel]

I took some liberty with formatting some of the existing text to it's easier to read, pls let me know what you think.

The main things that I added are:

• more text to the features section
• broken down getting started section by provider ollama and the rest (ideally we would have one for each provider)

TODO: I would like to add a section where we recommend 1 model for each hardware as you've already started in the Model support section

Fixes #164

[rjmacarthy]

Thanks, it's a lot better than before. Clearer and more helpful too, awesome! :)