docs: add files for RTD setup

[s-makin]

• Add docs directory to keep files together
• Add files necessary for RTD
• Add style sheets for "Ubuntu" style
• Add Diataxis outline and framework

Note, no docs files included yet, but this will
at least allow RTD to be set up for the project

[dbungert]

Thanks for getting this process started. I'd like to move the directory name to 'doc' to match the neighboring projects (cloud-init, curtin, netplan).

We do have an existing documentation directory in 'documentation', I would like a short README.md added in the 'doc' directory explaining the current state - basically, continue to add documentation changes to 'documentation' and this is the WIP location for future docs.

[s-makin]

Thanks for getting this process started. I'd like to move the directory name to 'doc' to match the neighboring projects (cloud-init, curtin, netplan).

We do have an existing documentation directory in 'documentation', I would like a short README.md added in the 'doc' directory explaining the current state - basically, continue to add documentation changes to 'documentation' and this is the WIP location for future docs.

Thanks Dan, I've made the changes you requested.

After I've done the initial setup on RTD, I'll start moving content but I'll need to confirm with you exactly which pages, and which versions of those pages, should be used. There are some pages in the Server Guide (namely in the "tutorial" section) which I think should be part of the Subiquity docs but are not in the documentation/ folder and I'd like to get your opinions on those.

[dbungert]

Thanks for this. I'm going to tweaking the wording on the README.md after we land this - I'd like doc to be the go forward location to match the other, similar, projects. (my fault for not explaining that correctly)