docs: added quickstart guide for S3-Keploy

[kpriyanshu2003]

What has changed?

1. Ran npx prettier --write '**/*.{js,md}' for formatting
2. Added docs in quick-start guide for S3-Keploy was missing.

This PR Resolves #2165

Type of change

Please delete options that are not relevant.

• [x] Documentation update (if none of the other choices apply).

How Has This Been Tested?

Yes, I have tested for the changes

• [x] npm run build was successful
• [x] Changes are visible as per expectations on the local build

Before:

After:

Checklist:

• [x] My code follows the style guidelines of this project.
• [x] I have performed a self-review of my own code.

[pratik-mahalle]

Hey @kpriyanshu2003, Thank you for raising the pr. Our team will review it soon