Remove manual Table of Contents in favor of autogenerated Page Table of Contents

[Eric-Arellano]

This is a better fix for the problem described in #1179.

@woodsp-ibm and I realized that it's redundant for us to have a manual Table of Contents section in the docs. qiskit_sphinx_theme will already auto-generate a page table of contents. It's duplicative to have our own manual section too.

We suspect that we picked up this habit from old docs that did it before qiskit_sphinx_theme used Pytorch to autogenerate the page table of contents. It's now an out-of-date practice that has a bad user experience & results in the issue in #1179.

[coveralls]

Pull Request Test Coverage Report for Build 5082182349

• 0 of 0 changed or added relevant lines in 0 files are covered.
• 1 unchanged line in 1 file lost coverage.
• Overall coverage decreased (-0.009%) to 87.471%

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Files with Coverage Reduction	New Missed Lines	%
qiskit_nature/second_q/drivers/psi4d/psi4driver.py	1	84.75%

Totals
Change from base Build 5054742046:	-0.009%
Covered Lines:	9404
Relevant Lines:	10751

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💛 - Coveralls

[mrossinek]

Thanks for fixing this!

[woodsp-ibm]

Was not quick enough to remove the backport label. We still have notebooks there right