fix documentation typo

Author: samblenny

CONTRIBUTING.md

@@ -30,7 +30,7 @@ As CircuitPython grows, there are more and more ways to contribute. Here are som
 
 ## Building CircuitPython: Getting started with C
 
-The CircuitPython core is implemented mostly in C. If you want to add suport
+The CircuitPython core is implemented mostly in C. If you want to add support
 for new boards, add features to the core, fix bugs in the core, or compile with
 special options (perhaps to make a debug build with UART logging), you will
 need to install a development environment with build tools.