Add explanantion on Opflow's ``StateFn(H, is_measurement=True) @ state``

[Cryoris]

Summary

Add a paragraph explananing Opflow's StateFn(H, is_measurement=True) @ state notation.

Details and comments

Also exchanges StateFn(H).adjoint() with StateFn(H, is_measurement=True) as the latter doesn't take the complex conjugate of the observable and is thus safer to use.

[review-notebook-app[bot]]

Check out this pull request on 

See visual diffs & provide feedback on Jupyter Notebooks.

---

Powered by ReviewNB

[HuangJunye]

@Cryoris It has been a while since this PR was submitted. Is this still relevant? Should I merge it?

[Cryoris]

Since Opflow has been deprecated, we don't need this anymore 🙂