docs(orderBy): clarify behavior of default comparator

[arw-travela]

Doc update to clarify behavior of the default comparator starting in v1.3.7. See #15293

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[arw-travela]

I signed it!

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CLAs look good, thanks!

[Narretz]

You can update the commit message by cloning your fork of this repo, amending the commit, and then force pushing it back.

[gkalpak]

This PR is for the 1.3.x branch. This is not maintained any more and even if we merged it, it wouldn't show up in the docs until there is a new release (and there will be no new release on the 1.3.x series 😃).

[arw-travela]

No problem - makes sense!