Improve readability of NGINX reverse proxy doc (#299)

[noxian-byte]

Problem: A user had reported that the content was hard to read through a Qualtrics survey.

Solution: The content was summarized and split into bullet points where possible in order to make it more digestible and easier to read for non-native English speakers.

This PR addresses Issue - reportedly difficult to read

[github-actions]

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[noxian-byte]

I have hereby read the F5 CLA and agree to its terms

[ADubhlaoich]

Doc changes generally LGTM! Put in some edit suggestions.

@y82 is the ultimate authority for NGINX core documentation.

The formatting changes for the directives are better, but I think there's still room there for something extra.

Possibly making the directive name a pseudo-heading with bold and dropping the colon: there's not enough of them to warrant a table, but even just breaking up the paragraph makes it more readable.

Thanks for the contribution! Let us know if there was anything about the process you found unclear.

[y82]

Hi @noxian-byte,

Thank you for your contribution. I've left some comments - once they're fixed we're good to go. Thanks again!

[noxian-byte]

Hi @y82

I have applied all of the changes.Please let me know if there is something else I should modify.

[mjang]

I appreciate your work @noxian-byte!

• Thank you for your contribution!
• Congratulations on getting your first contribution accepted and merged

FYI, I'm leaving the issue open as I hope for additional improvements.