docs: update README.md for examples/nextjs/starter

[BhumikP]

What

This PR includes documentation of Nextjs starter repo.

Related issue(s) :

• Update readme for examples/nextjs/starter (and merge in DEVELOPMENT.md)

Why

It helps user to understand the repository structure

How

PR addresses issue of documentation for the users.

Checklist

• I have read the Contribution Guidelines.
• My code is tested to the best of my abilities.
• My code passes all lints (ESLint, tsc, prettier etc.).
• My code has detailed inline documentation.
• I have added unit tests to verify the code works as intended.
• I have updated the project documentation accordingly.

[ashutoshgautams]

Middleware section just points to a separate doc without context, if it has to be like that maybe add it into learn more section.

[justlevine]

Middleware section just points to a separate doc without context, if it has to be like that maybe add it into learn more section.

This is a good point for enhancement, but its already 10.45PM IST, and I did as much other cleanup as I could. Feel free to follow up on this in future PRs.

Manual cleanup, rest can be handled iteratively.