C Cheat Sheet from #4896 (#5195)

* C Cheat Sheet from #4896

* alphabetize

free-programming-cheatsheets.md

@@ -29,6 +29,7 @@
 ### C
 
 * [C Reference Card (ANSI)](https://users.ece.utexas.edu/~adnan/c-refcard.pdf) (PDF)
+* [The C Cheat Sheet: An Introduction to Programming in C](https://sites.ualberta.ca/~ygu/courses/geoph624/codes/C.CheatSheet.pdf) - Andrew Sterian (PDF)
 
 
 ### C++