Introduction to Git: Change knowledge question link to appropriate resource

[goran1010]

Because

The current video resource that the knowledge question links to, doesn't actually answer the question it asks: "Why are Git and GitHub useful for a team of developers?".

The new link, from the lesson's 3rd assignment does contain the answer and is the appropriate resource to link to.

This PR

• Change https://youtu.be/1h9_cB9mPT8?t=162 link to https://docs.github.com/en/get-started/start-your-journey/about-github-and-git

Issue

Closes #29782

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