[gh-151] Fixed typo.

CONTRIBUTING.md

@@ -12,7 +12,7 @@ Code contributions are very welcome
 
 1. It's always recommended to find or submit an issue first, and comment that you want to do it.
 This is especially important if you want to implement new feature.
-Your effort might be lost if it's already in progress, or if there is a disagremeent about approach, etc.
+Your effort might be lost if it's already in progress, or if there is a disagreement about approach, etc.
 
 2. I have very specific opinions about UI design, code structure, patterns, features, etc.
 I might adjust or rewrite the code your submitted to match these ideas.