[WIP] Convert to RST for Read The Docs (RTD)

Using modified PR template from [TransformCore PR Checklist](https://github.com/TransformCore/documentation-templates/blob/master/contributions/Contributing.md)

| - Q. - | - A. - |
| ------ | ------ |
| Tickets | #114 |
| Type | Documentation |
| BC breaks? | yes |
| Deprecations? | yes |
| Docs | updated |
| Status | WIP |

What `:doc:` is doing then?