Add Reading list to math/cs

mathematics.md

@@ -1,3 +1,7 @@
+### Reading List
+- [Firewall](https://en.wikipedia.org/wiki/Firewall_(computing))
+- [Reverse Proxy](https://en.wikipedia.org/wiki/Reverse_proxy)
+
 ##  Mathematics                                                                  
 - [Matrix calculus](https://en.wikipedia.org/wiki/Matrix_calculus)               
 - [Small-angle approximation](https://en.wikipedia.org/wiki/Small-angle_approximation)