Update Concept of Operations

[dwagmuse]

I would like to add a bit of background theory to the documentation. The current overview (and everything else) is highly focused on the java implementation of Aerie. I would like to explain it from a system engineer's perspective: why we need a planner, the system problem it solves, and a little bit of a theoretical basis in control theory.

My suggestion is to add a section under Mission Modeling to explain basic theory, define terms, etc., to explain how to think about this before you jump into how to code it up.
We might also beef up the Concept of Operations to introduce and explain the planning context a bit more. Current documentation is from the POV of someone experienced in planning who understands the legacy problems Aerie is designed to fix. Probably better to just explain what it IS/DOES and why and maybe move the legacy stuff to a History section.

Coming at this from a system engineer's perspective, my goal is to make the docs explain Aerie to a system engineer user or stakeholder who wants to understand how/why they would use Aerie in a project context and not how to code it.
I'm willing to help update the docs to do this.