add few guides for bfs in graph

[Dungnope]

Because

Relevant to #29783, project Knight Travails is still ambiguous, I want to add two more links to help other learners understand BFS in graph before actually code this project

This PR

1. Link to youtube video how graph traversals with BFS and DFS
2. Next part of graph at Khan academy about graph, the second link is the next part of graph, using BFS for traversal

Issue

Related to #29783

Additional Information

Add two links is the minimum things I can do right now, after solve this project, I felt more motivations and want to share the way others can try to get depth understand before solving it.

Pull Request Requirements

• I have thoroughly read and understand The Odin Project curriculum contributing guide
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• The Because section summarizes the reason for this PR
• The This PR section has a bullet point list describing the changes in this PR
• If this PR addresses an open issue, it is linked in the Issue section
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• If any lesson files are included in this PR, they follow the Layout Style Guide

[CouchofTomato]

Can you explain why you think it's still ambiguous?

[Dungnope]

Can you explain why you think it's still ambiguous?

This project told me a very brief about graph with theories but I only understood BFS and DFS with BST, not graph, so I want at least comprehensive Graph traversal and think to solve the project

[mao-sz]

If you read the related issue you linked, being more explicit about BFS is actually not the direction we want to go with this. What we're already working on is a Graphs project to bridge the gap between Knight Travails and previous projects. But making KT more explicit with specific algorithm implementation is not the direction we want it to go.