[REQUEST]: Reference docs for @elastic/synthetics

[colleenmcginnis]

Description

We have some code comments in https://github.com/elastic/synthetics (for example expect.ts). We should consider building out those comments and use a tool like JSDoc to generate a complete reference for Synthetics.

However, we don't necessarily need to publish this on the elasitc.co website if it would become a maintenance burden. We could consider generating the docs, publishing them from the Synthetics repo, and linking directly to the generated docs from the Observability docs.

Resources

Related to #2603

Collaboration

TBD. The docs and product team will work together to determine the best path forward.

Point of contact.

Main contact: @colleenmcginnis

Stakeholders: @vigneshshanmugam @paulb-elastic