Update README.md with a Table of Contents

[shashankrushiya]

1. Which Jira issue is this PR addressing? Make sure that there is an accompanying issue to your PR.

   Not available, this is just an optional Enhancement

2. Fill out the following pre-review checklist:

   • I am adding a new automated test(s) to verify correctness of my new code
   • If this test skips Local Testing mode, I'm requesting review from @snowflakedb/local-testing
   • I am adding new logging messages
   • I am adding a new telemetry message
   • I am adding new credentials
   • I am adding a new dependency
   • [ x] If this is a new feature/behavior, I'm adding the Local Testing parity changes.
   • [ x] I acknowledge that I have ensured my changes to be thread-safe. Follow the link for more information: Thread-safe Developer Guidelines

3. Please describe how your code solves the related issue.

   Adding a table of Contents help in better navigation, especially since this file is long and covers multiple topics.

[github-actions]

Thank you for your submission, we really appreciate it. Like many open-source projects, we ask that you sign our Contributor License Agreement before we can accept your contribution. You can sign the CLA by just posting a Pull Request Comment same as the below format.

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I have read the CLA Document and I hereby sign the CLA

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[shashankrushiya]

I have read the CLA Document and I hereby sign the CLA