metadata API documentation doesn't mention v3

### Version Information

Server Version: 2.1.1

### What is the expected behaviour?

Metadata API seems to focus on v1 and v2, doesn't mention v3 except in some examples

### What is the current behaviour?

I'm just looking through documentations for metadata API calls and finding some conflicting information.

### How to reproduce the issue?

1. Go to https://hasura.io/docs/latest/graphql/core/api-reference/metadata-api/manage-metadata.html#

### Screenshots or Screencast

These are just examples.