Update link and added info in Forth section

[margaret-hu]

What does this PR do?

Add info | Improve repo

IMPORTANT

• Read our contributing guidelines.
• Is this a revision of a previously submitted PR? If so, STOP! Go back, reopen the PR, and add commit(s) the branch you previously submitted. Please don't make the job of reviewing more difficult by hiding previous work.

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:

• 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!

[github-actions]

Oh no 😟! Conflicts have been found.

Please 🙏, take a moment and address the merge conflicts of your pull request before we can evaluate it again.

Thanks in advance for your effort and patience ❤️!

[github-actions]

'This Pull Request has been automatically marked as stale because it has not had recent activity during last 60 days 😴

It will be closed in 30 days if no further activity occurs. To unstale this PR, draft it, remove stale label, comment with a detailed explanation or push more commits.

There can be many reasons why some specific PR has no activity. The most probable cause is lack of time, not lack of interest.

Thank you for your patience ❤️'