Mention DC instructions no longer supported

[jyu00]

URL to the relevant guide or resource

https://quantum.cloud.ibm.com/docs/en/guides/classical-feedforward-and-control-flow#qiskit-runtime-limitations

Select all that apply

• new content request
• typo
• code bug
• out-of-date content
• broken link
• other

Describe the fix or the content request.

In the Qiskit Runtime limitations section, we should also point out that for, while, and switch instructions are no longer supported.

For new content requests - if the request is accepted, do you want to write the content?

I can help the team by providing enough information or by referring them to a specific Subject Matter Expert to write the material