What do you mean by "add the content that you're alluding to"? This sentence introduce the paragraph on `ExecutionContext.global`. If you're refering to "requires some care" then read up a few lines, you'll get some content. If you're refering to "sufficient for most situations" then negate the previous ;)
Of course that kind of sentence can always be seen as superfluous - and I'm fine removing it, you decide - but to be honest it doesn't strike me given the current doc.