feat(docs): Add getting-started with installation

[Fleny113]

Add a getting-started page to the docs. The getting started will include the installation and desired proprieties explanation as they tend to be very confusing at first

[lts20050703]

LGTM!

I see that's there's a "TODO: Add a link to the page on how to use OAuth2 in Discordeno.". I think it's okay to merge this and do the TODO in a new PR.

As for "<!-- TODO: Do we want to keep this info box? Or rewrite a bit this --", I'm thinking of something like "Thank you for choosing Discordeno! Discordeno is designed to easily make scalable bots, so it might not be for you. However, we hope that you at least give it a try and don't hesitate to join and ask for help in our Discord server!"

If it sounds too "begging people" please let me know lol, I'm fine with the current text (also fine if the text was removed)

[Fleny113]

I think it's okay to merge this and do the TODO in a new PR.

It would be a bit too much for one pr, i don't want to forget about it, so i added a todo, that is it

I'm thinking of something like ...

I wanted to ask because i don't know what the best solution is, discordeno does have some not completely beginner friendly things (for example Desired Proprieties or the non-exiting caching by default) but it is still valuable imho to know, and i thought it sounded too "hard"

[lts20050703]

I'm reviewing this at 3AM so don't trust me lol, feel free to comment on any changes that doesn't make sense

[lts20050703]

LGTM!