[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 |

1. Is an **Internal** link

   From the documentation http://sphinx-doc.org/markup/inline.html#cross-referencing-documents 

   > Cross-referencing documents
   > There is also a way to directly link to documents:
   > :doc:
   > Link to the specified document; the document name can be specified in absolute or relative fashion. For example, if the reference :doc:`parrot` occurs in the document sketches/index, then the link refers to sketches/parrot. If the reference is :doc:`/people` or :doc:`../people`, the link refers to people.

   Therefore, an extension is not require - I read somewhere it would work for PDFs too.

2. Is an **External** link