stream: correct iterators in doc examples

[dmitris]

Correct the iterators used in examples to produce the described output.

Currently in https://docs.rs/async-std/1.10.0/async_std/stream/index.html#while-let-loops-and-intostream the text after the code snippet says "This will print the numbers one through five" but because the code uses stream::repeat(1u8).take(5), it will print 1 five times instead - modified to use from_iter(1..6). Similarly, in the Iinfinity" section https://docs.rs/async-std/1.10.0/async_std/stream/index.html#infinity, changed stream::repeat(1u8) to stream::from_iter(0u8) to produce the described result, "print the numbers 0 through 4".

I believe the Section "while let Loops and IntoStream" https://docs.rs/async-std/1.10.0/async_std/stream/index.html#while-let-loops-and-intostream has more problems. Is the into_stream used in this example? The explanation says: "we never called anything on our vector to produce a stream" - but as far as I see, there is no vector in the example, only async_std::stream::Repeat created with repeat - or a Stream in the modified example. Also IntoStream is supported only on unstable - I wonder if it would be better to rename the section to while let Loops and FromIter and talk about conversion of iterators into streams with from_iter instead of into_stream.

[dmitris]

@yoshuawuyts would appreciate if you could review the suggested change, or point out someone who could do it. Thanks!

[yoshuawuyts]

Looks good; thanks

[dmitris]

thanks @yoshuawuyts!

When will it make its way to https://docs.rs - after the next crate release?

Do you agree with the idea of changing the section header "while let Loops and IntoStream" to "while let Loops and FromIter" and talking about from_iter() instead of (or in addition to) into_stream? I can raise a PR if that sounds right in principle.