contrib: update broken image link in metadata types readme

[GavinRay97]

Description

Changelog

• CHANGELOG.md is updated with user-facing content relevant to this PR. If no changelog is required, then add the no-changelog-required label.

Affected components

• Server
• Console
• CLI
• Docs
• Community Content
• Build System
• Tests
• Other (list it)

Related Issues

Solution and Design

Steps to test and verify

Limitations, known bugs & workarounds

Server checklist

Catalog upgrade

Does this PR change Hasura Catalog version?

• No
• Yes
  • Updated docs with SQL for downgrading the catalog

Metadata

Does this PR add a new Metadata feature?

• No
• Yes
  • Does run_sql auto manages the new metadata through schema diffing?
    • Yes
    • Not required
  • Does run_sql auto manages the definitions of metadata on renaming?
    • Yes
    • Not required
  • Does export_metadata/replace_metadata supports the new metadata added?
    • Yes
    • Not required

GraphQL

• No new GraphQL schema is generated
• New GraphQL schema is being generated:
  • New types and typenames are correlated

Breaking changes

• No Breaking changes

• There are breaking changes:

  1. Metadata API

     Existing query types:

     • Modify args payload which is not backward compatible
     • Behavioural change of the API
     • Change in response JSON schema
     • Change in error code

  2. GraphQL API

     Schema Generation:

     • Change in any NamedType
     • Change in table field names

     Schema Resolve:-

     • Change in treatment of null value for any input fields

  3. Logging

     • Log JSON schema has changed
     • Log type names have changed