An introduction to Chakra UI – Design system, custom styling, and theming

[jasonfyw]

Implements issue #532

This PR covers additions in the following topics to the Chakra UI page

• Chakra UI design principles
• Styling components and prop-based styling
• Implementing responsive design
• Implementing custom themes

[jasonfyw]

Thank you for the insightful suggestions @PierreLessard! I've added the new section as requested 👍