M&B: Onboarding checklist

## Definition of done
Using the steps from https://docs.google.com/document/d/15Gkw0VYGvfAcyKgFOt1dBZ0K_qPllxAQGZ17KVJpxRE/edit?tab=t.lzl9jgw3pumd#heading=h.xe87j0w2blzg, create an onboarding checklist for M&B
- These steps aren't specific to a particular project.
- For the Initial setup section, we have [how tos](https://developer.konghq.com/how-to/?products=metering-and-billing), consider links or tiles to those with any notes, like service accounts recommended.
- Integration points and their APIs should also be included on this page
- A similar page to use for inspiration could be https://developer.konghq.com/insomnia/enterprise-onboarding/

## Information
DRP: Peter M.
Slack: https://kongstrong.slack.com/archives/C09BAEXTTM4/p1773333246203709

## Due date (optional)

## Size
L

Start with the linked Google Doc for the onboarding steps, then review the Metering and Billing how-to pages and the Insomnia enterprise onboarding page for structure and reusable patterns. Create an M&B onboarding checklist covering initial setup, links or tiles with notes, integration points, and their APIs; done means the checklist is published as a complete documentation page.

Written by the indexing model from the issue text.