Add information about creating classical bits

[beckykd]

URL, if applicable

No response

Describe the new content you are requesting.

In several error messages, we tell people to create more classical bits, but I can't find anywhere that we clearly tell people how to create classical bits. I feel like one of these guides would be a good place:

https://docs.quantum.ibm.com/guides/construct-circuits https://docs.quantum.ibm.com/guides/measure-qubits

If this new content request is accepted, do you want to write the content?

I will write a draft of the proposed content

[abbycross]

Does the info already in the Measure qubits guide section QuantumCircuit.measure_all method suffice?

Error code 7003 is an example of the message telling the user to create more classical bits (that's the only public one I see). Its message now points to the Measure qubits guide, though not specifically to the section I mentioned.