Migrate Hugo documentation to Sphinx

## Documentation request

As we implemented initial Sphinx documentation for the Island code, we can start and migrate the Hugo documentation to Sphinx

### Add a new page 🆕

**What documentation you'd like us to add?**
We need to add every single page that we have in Hugo as `.rst` in `monkey_island/docs/source`

**Where in the documentation tree?**
Recreate the same documentation tree that we have in Hugo in `monkey_island/docs/source`

## Tasks

- [ ] Migrate Hugo documentation to Sphinx