feat(topic): add differential calculus resource (#8496)

Added link to the 3blue1brown very relevant "essence of calculus" youtube playlist - following the contrib guidelines and the style in the "Linear algebra" content in the roadmap

Author: amirbabaei97

src/data/roadmaps/ai-data-scientist/content/differential-calculus@mwPJh33MEUQ4Co_LiVEOb.md

@@ -1,4 +1,4 @@
 # Differential Calculus
 
 - [@article@Algebra and Differential Calculus for Data Science](https://imp.i384100.net/LX5M7M)
-
+- [@video@Calculus Youtube Course](https://www.youtube.com/playlist?list=PLZHQObOWTQDMsr9K-rj53DwVRMYO3t5Yr)