Reflect support for query parameters in Query Results Data Source docs

[sugawani]

• Query parameters are now supported in Query Results Data Source (QRDS) as of redash/redash#5723
• Updated the docs to show how to use param_query_<query_id>_{<URL ENCODED KEY=VALUE>}
• Removed the outdated warning about QRDS not supporting parameters

This is my first time submitting a PR, so please let me know if there are any other responses needed.

NOTE: I'm not fully confident in my English or understanding of Redash internals, so feel free to point out any mistakes or improvements.
Thanks!

[sugawani]

@lucydodo
The query parameter in QRDS is very useful, but since it is not documented, it’s difficult to understand how to use it properly.
I would greatly appreciate it if you could review my pull request.

[lucydodo]

LGTM! Thanks for the contribution. and I missed your PR submission. I apologize for the delay in reviewing it.