Landingpage update

[sekyondaMeta]

Description

Updates in this PR:

1. Landing page update to make it easier to navigate. Similar to TorchAudio Landin page
2. Added FAQs to side nav and removed the sphinx/resuirements.txt link from side nav
3. Hopefully fix issue Docs are not complete #2048
4. Simple updates to performance doc (this is a work in progress) issue Performance Optimization guide updates #2334
5. Renamed old index.md to indexOLD.md for record keeping.

Type of change

Please delete options that are not relevant.

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)

Feature/Issue validation/testing

Built tests locally on computer see attached screenshots:

Checklist:

• Did you have fun?
• Have you added tests that prove your fix is effective or that this feature works?
• Has code been commented, particularly in hard-to-understand areas?
• Have you made corresponding changes to the documentation?

[codecov]

Codecov Report

Merging #2418 (036f7a3) into master (4e21262) will not change coverage.
The diff coverage is n/a.

❗ Current head 036f7a3 differs from pull request most recent head 9a6aba6. Consider uploading reports for the commit 9a6aba6 to get more accurate results

@@           Coverage Diff           @@
##           master    #2418   +/-   ##
=======================================
  Coverage   72.01%   72.01%           
=======================================
  Files          78       78           
  Lines        3648     3648           
  Branches       58       58           
=======================================
  Hits         2627     2627           
  Misses       1017     1017           
  Partials        4        4           

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[sekyondaMeta]

Description

Updates in this PR:

1. Landing page update to make it easier to navigate. Similar to TorchAudio Landin page
2. Added FAQs to side nav and removed the sphinx/resuirements.txt link from side nav
3. Hopefully fix issue Docs are not complete #2048
4. Simple updates to performance doc (this is a work in progress) issue Performance Optimization guide updates #2334
5. Renamed old index.md to indexOLD.md for record keeping.

Type of change

Please delete options that are not relevant.

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)

Feature/Issue validation/testing

Built tests locally on computer see attached screenshots:

Checklist:

• Did you have fun?
• Have you added tests that prove your fix is effective or that this feature works?
• Has code been commented, particularly in hard-to-understand areas?
• Have you made corresponding changes to the documentation?

Also adding an update to Sphinx 5.0.0 as that is what most of the other PyTorch Docs are using plus 4.0.3 seems to be breaking when tested locally.,

[msaroufim]

Is the indexOld file still needed?

[sekyondaMeta]

Is the indexOld file still needed?

No, but keeping it for now in case we need to revert back to it for whatever reason. Once the PR lands and everything seems fine, I will remove it on the next PR I land.