Fix 404 link: /documentation/references/asyncapi

[yada]

Broken link (404)

• URL: https://microcks.io/documentation/references/asyncapi
• HTTP status: 404
• Found on: https://microcks.io/documentation/references/test-endpoints/

What to do

• Update the source page to point to the correct/current AsyncAPI reference page (or remove the link if obsolete).
• If the content moved, prefer the new canonical documentation URL.

Help needed

If you’re unsure what the correct replacement URL should be, please comment on this issue and we’ll help identify the right target.

[yada]

Fixed, see: #506