Fixing a grammatical mistake.

Thanks @TheSpyder!

README.md

@@ -20,7 +20,7 @@ Notes:
 * If you are having problems finding 'jni.h'. Make sure you have the JDK installed not just the JRE. If you are using
       OpenJDK you want the openjdk-7-jdk package, not openjdk-7-jre.  _Mavericks users see [Issue #86](https://github.com/nearinfinity/node-java/issues/86) if you run into this._
 
-### Installatin OSX
+### Installation OSX
 
 * If you run into strange runtime issues, it could be because the Oracle JDK does not advertise itself as available for JNI.  See [Issue 90](https://github.com/joeferner/node-java/issues/90#issuecomment-45613235) for more details and manual workarounds.  If this does occur for you, please update the issue.