Draft Primer to replace Getting Started section of documentation

[EricReese15]

As discussed, we've been working on a replacement to the current format for the Getting Started section of the documentation. To do that, I've drafted a series of pages that together form a "Primer." The primer will be organized around answering four main questions, with each having their own section within the primer, plus a landing page for the Primer to provide general orientation for users to the purpose of the primer.

What is OCDS?
How does OCDS work?
What does OCDS data look like?
How can I implement OCDS?

Within each page, there will be a standard structure and order of elements: objectives, video inset, detail on key concepts, and further resources (OCDS documentation pages and other OCP materials).