fix 'inconsistency' spelling in README (#772)

Author: ilhamwahabi

README.md

@@ -291,7 +291,7 @@ You can toggle the presenter or overview mode by pressing respectively `alt+p` a
 
 Fullscreen can be toggled via browser options, <kbd>Alt/Option</kbd> + <kbd>F</kbd>, or by pressing the button in the bottom right corner of your window.
 
-Note: Right now, this works well when browser window itself is not full screen. When the browser is in fullscreen, there is an issue [#654](https://github.com/FormidableLabs/spectacle/issues/654). This is because we use the browser's FullScreen API methods. It still works but has some inconstiency.
+Note: Right now, this works well when browser window itself is not full screen. When the browser is in fullscreen, there is an issue [#654](https://github.com/FormidableLabs/spectacle/issues/654). This is because we use the browser's FullScreen API methods. It still works but has some inconsistency.
 
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