create autodiff doc for mcsolve

[rochisha0]

show the gradient calculation for mcsolve

[coveralls]

Pull Request Test Coverage Report for Build 10607968139

Warning: This coverage report may be inaccurate.

This pull request's base commit is no longer the HEAD commit of its target branch. This means it includes changes from outside the original pull request, including, potentially, unrelated coverage changes.

• For more information on this, see Tracking coverage changes with pull request builds.
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• For a quick fix, rebase this PR at GitHub. Your next report should be accurate.

Details

• 0 of 0 changed or added relevant lines in 0 files are covered.
• 6 unchanged lines in 2 files lost coverage.
• Overall coverage decreased (-0.2%) to 90.303%

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Files with Coverage Reduction	New Missed Lines	%
src/qutip_jax/measurements.py	1	98.92%
src/qutip_jax/settings.py	5	70.59%

Totals
Change from base Build 9842191187:	-0.2%
Covered Lines:	1220
Relevant Lines:	1351

---

💛 - Coveralls

[Ericgig]

I merged the changes from dev.major into master could you check that everything works and remove the note about it.

[rochisha0]

@Ericgig I've tested this and it is working.

[Ericgig]

Let's not use qt and qjax in example.

[Ericgig]

Since this is the only explanation of the example, let's not put it in a note.

[Ericgig]

Good enough.
The explanation feels a little dry but it shows how it works.