docs: add video link for visual explanation of event loop

[yashraj021]

Adds a link to a video by Bert Belder from the official Node.js YouTube channel. The video provides a visual walkthrough of the event loop and its phases, helping readers better understand the diagram and concepts in the "Event Loop Explained" section.

Placed the link directly after the event loop diagram, where readers are first introduced to the phase concept.

Description

This PR adds an inline tip linking to a video by Bert Belder on the official Node.js YouTube channel. The video provides a visual explanation of how the Node.js event loop works. The link is placed right after the event loop diagram to offer readers an immediate opportunity to see the concept visually explained.

Validation

Manually verified by checking the rendered markdown in the browser preview. Confirmed that:

• The link is properly rendered

• Placement feels natural directly below the event loop diagram

• The video enhances clarity without disrupting reading flow

Related Issues

Check List

• I have read the Contributing Guidelines and made commit messages that follow the guideline.
• I have run pnpm format to ensure the code follows the style guide.
• I have run pnpm test to check if all tests are passing.
• I have run pnpm build to check if the website builds without errors.
• I've covered new added functionality with unit tests if necessary.