added some free next js courses

[AmardeepKesharwani]

What does this PR do?

Add resource(s) | Remove resource(s) | Add info | Improve repo

For resources

Description

Why is this valuable (or not)?

How do we know it's really free?

For book lists, is it a book? For course lists, is it a course? etc.

Checklist:

• Read our contributing guidelines.
• Search for duplicates.
• Include author(s) and platform where appropriate.
• Put lists in alphabetical order, correct spacing.
• Add needed indications (PDF, access notes, under construction).
• Used an informative name for this pull request.

Follow-up

• Check the status of GitHub Actions and resolve any reported warnings!

[bugbunnyy]

Please ensure that the courses you add to the Next.js category are alphabetically arranged.
This and the the above changes(comment) will allow you to solve linter warnings.