Add link to resource (#5046)

Refactoring Guru added to the computer science roadmap Design Patterns section.

src/data/roadmaps/computer-science/content/111-design-patterns/index.md

@@ -5,4 +5,5 @@ Design patterns are solutions to common problems in software design. They are fo
 Visit the following resources to learn more:
 
 - [Design Patterns - Wikipedia](https://en.wikipedia.org/wiki/Software_design_pattern)
-- [Design Patterns for Humans](https://github.com/kamranahmedse/design-patterns-for-humans)
+- [Design Patterns for Humans](https://github.com/kamranahmedse/design-patterns-for-humans)
+- [Refactoring Guru - Design Patterns](https://refactoring.guru/design-patterns/)