add notes

slides/pages/materials.md

+---
+title: Useful Materials
+layout: two-cols
+---
+
+# Notes
+
+- Cover other tools such as `gdb` and `make` next time (depends on the demand)
+- Unit Testing in C
+
+## Other Useful Resources
+
+- [The Missing Semester of Your CS Education](https://missing.csail.mit.edu/)
+- [DevDocs](https://devdocs.io/)
+- [tldr](https://github.com/tldr-pages/tldr)
+

slides/slides.md

@@ -74,3 +74,7 @@ transition: slide-left
 src: ./pages/clang-5.md
 ---
 
+---
+transition: slide-left
+src: ./pages/materials.md
+---