docs(all): add toc to README.md and CONTRIBUTING.md

[ijemmy]

Description of your changes

Add table of contents to CONTRIBUTING.md and README.md

Both files are large and hard to navigate. Adding ToC will help readers to see the over all structure and can navigate to the relevant content quicker.

How to verify this change

Preview the Markdown File and click on the links in ToC.

Related issues, RFCs

N/A

PR status

Is this ready for review?: YES
Is it a breaking change?: NO

Checklist

• My changes meet the tenets criteria
• I have performed a self-review of my own code
• I have commented my code where necessary, particularly in areas that should be flagged with a TODO, or hard-to-understand areas
• I have made corresponding changes to the documentation
• I have made corresponding changes to the examples
• My changes generate no new warnings
• The code coverage hasn't decreased
• I have added tests that prove my change is effective and works
• New and existing unit tests pass locally and in Github Actions
• Any dependent changes have been merged and published in downstream module
• The PR title follows the conventional commit semantics

Breaking change checklist

• I have documented the migration process
• I have added, implemented necessary warnings (if it can live side by side)

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[dreamorosi]

Thanks for the PR!

[orozcoadrian]

Reminder that github has a built-in (and automatically-generated/always up-to-date) ToC ux feature.

Having multiple ways to navigate is probably ok, we'll just need to remember to check if the ToC needs updating whenever content in the page changes.

[saragerion]

Thanks for this PR! I think this will definitely improve the docs experience. I added some minor suggestions :)

[saragerion]

@orozcoadrian thanks for bringing this up. Indeed you are right. In my opinion, The downside of the Github ToC is:

• 1 click necessary
• hard to scroll and read the long list of headings

Hence the need for this more manual approach.

[dreamorosi]

+1 on having an explicit in-text ToC.

I use GitHub on mobile more than half of the time and it doesn't support the feature yet :(

Downside of this is that we'll have to remember to keep it updated, but hopefully these docs won't be changing all the time.