Add rich, textual, and termynal libraries to Terminal Rendering section

[MuhammadUsmanGM]

This PR adds three libraries to the Terminal Rendering section:

• rich: Render rich text, tables, markdown, progress bars, and more in the terminal.
• textual: Build modern TUI apps using Rich with widgets and layout support.
• termynal: A customizable terminal-style interface often used for tutorials and docs.

All three are popular, well-documented, and actively maintained.

[glukkluk]

Hi. Yes, these libraries are really great. I personally had no experience with a termynal library. But the rich and especially the textual libraries impressed me!