v3 introduces some regression if it comes to `parameters` description

In short, no more JSON schema for parameters in v3 -> https://github.com/asyncapi/spec/blob/next-major-spec/spec/asyncapi.md#user-content-parameter-object

But I just discovered one example that actually uses `pattern` keyword from JSON schema -> https://github.com/asyncapi/spec/blob/master/examples/rpc-client.yml#L21

- Now, it is not something that I see in a production use cases, just one of our examples
- Also, affected users might be not many

I think that the impact is small, will not affect adoption and it is completely fine if we add it v3.1

But I want to make sure other codeowners don't see a problem

cc codeowners @fmvilas @dalelane @smoya @char0n

fyi @jonaslagoni

Read the Parameter Object section in spec/asyncapi.md and compare it with the pattern example around line 21 of examples/rpc-client.yml. Determine whether the v3 change intentionally removes this JSON Schema keyword, then document the agreed compatibility decision and update the affected specification or example accordingly.

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