[Versioned APIs] Versioned interfaces dev docs guide (#150705)

## Summary

Adds a dev docs guide for the core-approved versioning strategy. This
strategy is subject to some iteration but is based on the work we did
for the Saved Objects Management plugin in
#149495.

Closes #149929

## How to test

1. Run `./scripts/dev_docs.sh`
2. Navigate to "Versioning interfaces" in the side nav menu

---------

Co-authored-by: Luke Elmers <[email protected]>