Release notes for 0.104.0 (nushell#1836)

* Release notes for `0.104.0`

Please add your new features and breaking changes to the release notes
by opening PRs against the `release-notes-0.104.0` branch.

## TODO
- [ ] PRs that need to land before the release, e.g. [deprecations](https://github.com/nushell/nushell/labels/deprecation) or [removals](https://github.com/nushell/nushell/pulls?q=is%3Apr+is%3Aopen+label%3Aremoval-after-deprecation)
- [ ] add the full changelog
- [ ] categorize each PR
- [ ] write all the sections and complete all the `TODO`s

* release notes 0.104.0: datetime handling highlights (nushell#1873)

* release notes 0.104.0: datetime handling highlights

* fix typos workflow

* update after further merges

* Notes for #15511 (substring match algorithm) (nushell#1896)

* started sorting PRs for 0.104.0

* updated 0.104.0 blog date

* sorted more PRs

* Final updates before ToC

* Final with ToC

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Co-authored-by: Loïc Riegel <[email protected]>
Co-authored-by: Tim 'Piepmatz' Hesse <[email protected]>
Co-authored-by: NotTheDr01ds <[email protected]>

Author: 4 people