Create a developer guide for using Cavalcade

(Moving @owaincuvelier's issue to the public repo.)

Might be good to write a developer guide on cavalcade, how to, do’s and dont’s, pro tips, limitations, examples of when you might want to offload work to cavalcade, how to space it out, memory constraints, and debugging tips.
This might be useful:
https://hmn.slack.com/archives/C098H3YQM18/p1754313231595799

### Acceptance Criteria
- [ ] Write how cavalcade is different from other services
- [ ] Write limitations
- [ ] Write examples of when you might want to offload work to cavalcade
- [ ] Write how to use it in general (do’s and dont’s, pro tips)
- [ ] Write how to use it for specific scenarios (mission critical jobs, many async jobs/scalling jobs)
- [ ] Write debugging tips

### Ready for Work Checklist

Is this ticket ready to be worked on? See
[the Play Book Definition of Ready](https://playbook.hmn.md/play/product/definition-of-ready/)

- [x] Is the title clear?
- [x] Is the description clear and detailed enough?
- [x] Are acceptance criteria listed?
- [x] Have any dependencies been identified? (Optional)
- [x] Have any documentation/playbook changes been identified? (Optional)
- [x] Is an estimate or time box assigned?
- [x] Is a priority label assigned?
- [ ] Is this ticket added to a milestone?
- [ ] Is this ticket added to an epic? (Optional)

### Completion Checklist

Is this ticket done? See
[the Play Book Definition of Done](https://playbook.hmn.md/play/product/definition-of-done-2/)

- [ ] Has the acceptance criteria been met?
- [ ] Is the documentation updated (including README)?
- [ ] Do any code/documentation changes meet project standards?
- [ ] Are automatic tests in place to verify the fix or new functionality?
- [ ] Or are manual tests documented (at least on this ticket)?
- [ ] Are any Playbook/Handbook pages updated?
- [ ] Has a new module release (patch/minor) been created/scheduled?
- [ ] Have the appropriate `backport` labels been added to the PR?
- [ ] Is there a roll-out (and roll-back) plan if required?