[mediaqueries] Fix typo

Closes #1231

Author: frivoal

mediaqueries/Overview.bs

@@ -1265,7 +1265,7 @@ Display Update Frequency: the 'update' feature</h3>
 		<dd>
 			The layout may change dynamically according to the usual rules of CSS,
 			but the output device is not able to render or display changes quickly enough
-			for them to be percieved as a smooth animation.
+			for them to be perceived as a smooth animation.
 			Example: E-ink screens or severely under-powered devices.
 
 		<dt><dfn>fast</dfn>