Generally improve "Hello world" page

[frankharkins]

URL to the relevant documentation

https://docs.quantum.ibm.com/start/hello-world

Select all that apply

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• out-of-date content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

Describe the fix.

The page feels really convoluted for what is supposed to be the simplest possible Qiskit program. I imagine our time to hello world is pretty poor.

Things we could improve:

• Remove the long admonition on bit-ordering
• Remove the long admonition on ISA circuits (this especially feels like it's for existing users)
• Remove any jargon not needed for the example (ISA, PUB)
• Maybe simplify the example code

[Eric-Arellano]

Remove any jargon not needed for the example (ISA, PUB)

We should probably use the Sampler primitive so we don't need to explain PUB and use a list of circuits instead.

[frankharkins]

Sadly that doesn't seem like it'll fly (see #699 (comment)). It might still be possible to avoid focussing on "PUB" by just saying "circuit + observables".

[abbycross]

Will/should/could any of #1158 satisfy the fixes requested here?

[beckykd]

Will/should/could any of #1158 satisfy the fixes requested here?

Seems sensible to pause this work until @kaelynj finishes #1158

[beckykd]

Remove any jargon not needed for the example (ISA, PUB)

We should probably use the Sampler primitive so we don't need to explain PUB and use a list of circuits instead.

We could just say something like "Ensure the circuits will run on the backend" and call them "ISA"

[frankharkins]

Yep will close as I think Kaelyn's PR addresses most of these issues.