Update documentation for non-developers

[JonHMChan]

For myself, @ErinCorleyGray and @hairboat to work on. I've given both point people on the community and marketing teams a training on the workflow, it's time to reflect any gaps in the README.md to make sure anyone knows how to use the blog. Some things to consider:

• Make the create file, commit, pull request, merge workflow through the GitHub interface very clear. Take someone step-by-step with screenshots/gifs.
• Make the templates for all new files easy. This includes adding authors, posts, and tags
• Image workflow. How to upload images, reference them, and modify them (alignment, sizing, captions)
• Draft workflow. How people create drafts, collaborate on them, and eventually publish them? How about reviewing changes?
• How do we schedule and manage a constant stream of content? I imagine this is a Trello board @ErinCorleyGray ?
• Who are the point people for questions about the blog? I'm assuming @ErinCorleyGray and @hairboat for respective teams, and myself for anything else.
• Suggesting changes using issues.

Anything else I'm missing?

[JonHMChan]

@ErinCorleyGray and @hairboat do we think the documentation is sufficient as is? I'm thinking of shipping very soon.

[ErinCorleyGray]

@JonHMChan I think most of it is good, though I think we're still missing some of the image & draft workflow requests. Create, commit, pull request etc is much better. Also missing the stream of content part, but that obviously hasn't been determined yet.

[hairboat]

Do I have to define a source in my header material if I'm just writing a new post?

[hairboat]

Docs say .md but all the posts are .markdown. Can files be either, or is only one correct?