docs: add numfocus affiliation (marimo-team#5267)

marimo is officially a NumFocus affiliated project!

Author: akshayka

README.md

@@ -278,6 +278,13 @@ We're building a community. Come hang out with us!
 - 🎥 [Subscribe on YouTube](https://www.youtube.com/@marimo-team)
 - 🕴️ [Follow us on LinkedIn](https://www.linkedin.com/company/marimo-io)
 
+**A NumFOCUS affiliated project.** marimo is a core part of the broader Python
+ecosystem and is a member of the NumFOCUS community, which includes projects
+such as NumPy, SciPy, and Matplotlib.
+
+<img src="https://raw.githubusercontent.com/marimo-team/marimo/main/docs/_static/numfocus_affiliated_project.png" height="200px" />
+
+
 ## Inspiration ✨
 
 marimo is a **reinvention** of the Python notebook as a reproducible, interactive,