Improve Javadoc Comments

**Description:**
The current Javadoc comments in the **LibraryMan** project can be improved to enhance clarity and provide more beginner-friendly explanations. This will help new contributors better understand the code and contribute more easily.

**Tasks:**
1. Review the existing Javadoc comments across all classes and methods.
2. Simplify technical jargon and provide clear explanations.
3. Add examples where necessary to demonstrate how methods and classes are used.
4. Ensure consistency in formatting and language throughout the codebase.
5. Follow best practices for writing Javadoc comments:
- Briefly describe the purpose of the class or method.
- Explain all parameters and return values.
- Highlight any exceptions thrown by the method.
- Include relevant tags (e.g., `@param`, `@return`, `@throws`).

**Requirements:**
- Basic knowledge of Java and Javadoc format.
- Willingness to make the comments approachable for beginners.

**Additional Notes:**
Feel free to ask any questions or request clarifications in the comments below. Let's make this project more accessible to new contributors! 😊