added C source mockup

README.md

@@ -1,7 +1,10 @@
 
-# Hack: a typeface designed for source code
+## Hack: a typeface designed for source code
 
 <img src="img/hack-specimen.png" alt="Hack-a monospaced sans-serif font for source code" width="728">
+<br>
+<img src="img/c-mockup.png" alt="C source code example" width="728">
+
 
 ### About