Some of the icons are not self-explanatory, they need tooltips saying what they do

From time to time i see ppl using data instead of body which is wrong.
happened just recently in node-fetch/node-fetch#481 (comment)

how do you feel about adding a little warning message that can only appear once. (kinda like node reports that you are using experimental apis)

if ('data' in bodyInit && notWarned) {
  console.warn('use body i

It should cover when you'd use and how to use:

• parEvalMap/Unordered
• parJoin
• concurrently
• merge*

There's the page on Queue/Topic/etc but there's not a great single page on the operations directly on Stream. The Guide section on concurrency is very short and doesn't cover some of the most common operations (parEvalMap especially)