Feature/docs

[Theoreticallyhugo]

I've attempted to write docs that are easy to navigate and mention every single option that is available in our project, in order to allow for easier customisation.
the docs are split into three parts.

• the installation, which ive split off, but not changed in any way beyond that
• the color theming, which was added in a previous pr
• the CONFIG.md which explains every configuration option besides color theming

this pr is lacking explanations on the plugins fossil and terraform, because i honestly dont know what they are doing, and i have not yet been interested in looking into them very much, as this was quite the endeavour already.
additionally ive barely changed the README.md. while i feel like the features section is lacking a concept, i also wasnt too sure how to refactor it, so ill leave that to another pr.

so, all in all, we now have docs describing all plugins and configuration options. everything is linked for easy navigation, and the plugin list is sorted alphabetically.

i was thinking about adding info on non-bash external dependencies for each plugin. please let me know what you think about that.

[fvincenzo]

@Theoreticallyhugo Amazing job! I will put some time away over the weekend to review your series! 😄 I might learn something new!