Clarify terminology and role names

[aaaaalbert]

This isn't a big issue right now, but we'll want to start using a consistent terminology in our website and docs to make sure it's always obvious who the target audience is. For example, the "Using EdgeNet" page mentions "developers"; actually, the paragraph is relevant for experimenters using EdgeNet.

Potential problems

• user, end user --- I suggest "experimenter" instead
• website --> Could be this repo or the portal or the dashboard, so choose wisely
• operator --> Make clear what component they control, e.g. "portal operator"

You can possibly spot other instances, please list them here.

[boldt]

I agree with the term experimenter