Improved documentation for htmx:confirm event and examples for implementing sweetalert

[eduardolat]

Description

This PR is an update of the #2868 PR, sorry for the delay but I was very busy with my work.

I've read @Telroshan comments and have clarified it further so that everyone understands how it works.

I've also modified the file www/content/examples/confirm.md since the example didn't work correctly and I've added some comments clarifying how it works.

I hope this time everything is much clearer, I look forward to your comments, thank you very much!

Checklist

• I have read the contribution guidelines
• I have targeted this PR against the correct branch (master for website changes, dev for
  source changes)
• This is either a bugfix, a documentation update, or a new feature that has been explicitly
  approved via an issue
• I ran the test suite locally (npm run test) and verified that it succeeded

[alexpetros]

@Telroshan this looks reasonable to me, let me know what you think

[Telroshan]

Good inline comments to clarify, and it's cool that you added a basic example to instruct the general process!
Just allow me one question and I'll stop bothering you 😆