Foundations/ Revisiting RPS: Add lesson overview and knowledge check

[maahsnd]

Because

The "Revisiting RPS" lesson lacks both a "lesson overview" and a "knowledge check." Add both to align with standard lesson format. This will ensure consistency across the curriculum. Standardized structure improves clarity and user experience.

This PR

• Add a lesson overview section. The lesson covers how to use git branches (create, merge, delete, best practices, use cases).
• Add a knowledge check section. Reference the general concept of branches, branch creation, branch merging, and one use case.

Issue

Closes #27332

Additional Information

Pull Request Requirements

• [x] I have thoroughly read and understand The Odin Project Contributing Guide
• [x] The title of this PR follows the location of change: brief description of change format, e.g. Intro to HTML and CSS lesson: Fix link text
• [x] The Because section summarizes the reason for this PR
• [x] The This PR section has a bullet point list describing the changes in this PR
• [x] If this PR addresses an open issue, it is linked in the Issue section
• [x] If any lesson files are included in this PR, they have been previewed with the Markdown preview tool to ensure it is formatted correctly
• [x] If any lesson files are included in this PR, they follow the Layout Style Guide