Docs: Configuration file pages as explanation and reference (Diátaxis) (#10416)
* Scissor out and refine changes from #9921
* Polish intro sentences
* Add how-to reference
* Do some content updates.
* Emoji ⚖️
* fix mini err
* typo fix
* typo fixes
* Adds a seealso to v2 reference -- many people are visiting the reference directly (because we didn't have any other resources), should add the how-to
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Co-authored-by: Eric Holscher <25510+ericholscher@users.noreply.github.com>