doc,stream: remove wrong remark on readable.read

[jscissr]

The returned chunk is never longer than size, if I read the code correctly. I even tested it:

const stream = require('stream')

const readable = new stream.Readable({
  read (size) {
    this.push(Buffer.from('0123456789'))
    this.push(null)
  }
})

readable.on('readable', () => {
  let buf
  while ((buf = readable.read(4))) {
    console.log(buf)
  }
})

Output:

<Buffer 30 31 32 33>
<Buffer 34 35 36 37>
<Buffer 38 39>

Even tough the stream has ended, the data returned does not exceed size bytes.

Checklist

• documentation is changed or added
• commit message follows commit guidelines

Affected core subsystem(s)

stream

[jasnell]

unrelated change?

[jscissr]

I don't know from where this commit appeared.It might be related to the "allow edits from maintainers" option on the pull request. Or maybe this commit was deleted from master, but is still in my branch?
It also affects #15013

[jscissr]

This seems to be the reason. I will rebase on master.

[mcollina]

LGTM without the spurious changes.

[jscissr]

Did a rebase now.

[jasnell]

Landed in 8987ae8