Add Terminology section

[mmccool]

Add definitions for the following terms:

• [x] Edge
• [x] FaaS (differentiate stateful and non-stateful workloads)
• [x] Edge Cloud
• [x] Edge Resource (more general than Edge Cloud, includes for instance a user-owned desktop providing an offload target)
• [x] Migration (diff live and application-directed migration)
• [x] Computing Resource (might be edge, cloud, or client)
• [x] Client
• [x] CDN
• [x] MEC
• [x] Workload (e.g. packaged definition of compute work required)
• [x] Cloud

It was also suggested in the meeting that we should look for existing definitions that we can cite rather than reinventing new terms. Here are some possible sources:

• IIC - Industrial Internet Association; note they merged with OpenFog, which addressed edge computing
• ISO - for example, https://www.iso.org/standard/74846.html
• ITU-T (focus on network operators, where Edge is often called "MEC" for "Multi-access Edge Computing")
• ETSI - IoT, but overlaps a bit with edge computing
• IETF - especially for protocol-related terms, but there are some survey documents on edge computing
• Plattform Industrie 4.0

In some cases definitions may conflict though (I remember long arguments about "fog" vs. "edge" that I don't particularly want to revisit...). Also, this is a big job even just going through all the existing standards. I suggest we start with the terms we are actually using and then checking individually if we are using them in a way consistent with existing standards. We could also just pick one and go with it (e.g. ISO, which I will review).

[mmccool]

PR #10 includes some basic definitions for all of the above but is light on external references. If you want to make suggestions on the PR to replace definitions with externally-defined "official" ones, with references, that would be totally fine and good.