Add: add user guide component and update layout

[Aditya-JOSH]

Description

This PR introduces a comprehensive user guide component to SpendWise, designed to walk users through the application's main features and common workflows. It provides step-by-step instructions, screenshots, and links to documentation, greatly improving onboarding and in-app user support. The remaining parts of the guide and any further updates can be completed once the code is updated accordingly.

Type of Change

• Bug fix
• New feature
• Breaking change
• Documentation update

Changes Made

• Added a new UserGuide React component under components/UserGuide.js, presenting detailed onboarding instructions and feature walkthroughs.
• Integrated relevant UI screenshots (login, signup, budgets, transactions, etc.) into the project’s src/assets/images/ directory for better visual guidance.
• Updated layout and sidebar to include a visible “Docs” link, directing users to the user guide.
• Enhanced app routes to include /user-guide, ensuring easy navigation to onboarding content.
• Applied new CSS rules for .user-guide and .blue-link in App.css for consistent and accessible guide presentation.
• Wrote stepwise descriptions for signup, login, budgeting, transaction tracking, and help.
• All content is written and structured for clarity and new user ease-of-use.

Testing

Describe how you tested these changes:

• Unit tests added/updated
• Integration tests pass
• Manual testing performed

Screenshots (if applicable)

Related Issues

Closes #23

[Limeload]

@Aditya-JOSH Good work!

[Aditya-JOSH]

@Aditya-JOSH Good work!

Tysm 🙌