Rename repository to better suit usage

This repo is useful for storing auto-generated information outside of just the vehicle parameters, as evidenced by the inclusion of MAVLink messages in #7.

I think we should rename the repo accordingly, to reduce future confusion.

There doesn't seem to be a consistent standard across the ArduPilot repos, but as a few potential options:
- `Metadata` (like `Datasheets`)
- `VehicleMetadata` or `FirmwareMetadata` (like `CustomBuild`)
- `ardupilot_metadata` (like `ardupilot_wiki`)
- `auto-parsed-data` (like `node-mavlink-mappings`)

Review issue #7 and the repository description to understand the current scope beyond vehicle parameters. Compare the proposed names with conventions across ArduPilot repositories, then confirm one name and apply the repository rename. Done means the project has an agreed new name without future confusion about its contents.

Written by the indexing model from the issue text.