Might be useful to divide WhateverData operators into event-based vs streaming

[jonnew]

Add page in introductory content explaining the following Data operator types and their effects.

Event Types WhateverData operators

• Produce data on some external, asynchronous event
• Example: digital inputs, lighthouse receivers

Streaming WhateverData operators

• Polled by hardware at regular intervals
• Example: analog inputs on breakout board