Move FDS documentation from docs-dev repository to app repository

It's probably best if we moved the FDS documentation to this app repository

The documents for the FDS are located in [the docs-dev repository](https://github.com/impact-space/docs-dev)

Start by reviewing the FDS documents in the linked docs-dev repository and the app repository's existing documentation structure. Move the relevant FDS documentation into the app repository, preserving the documents, and verify that the resulting documentation is present there.

Written by the indexing model from the issue text.