Minor typo "plaing" > "placing" (#1113)

Author: patrickhlauke

mediaqueries/Overview.bs

@@ -699,7 +699,7 @@ Combining Media Features {#media-conditions}
 
 	* Alternately, two or more media features can be chained together,
 		such that the query is true if <em>any</em> of the media features are true,
-		by plaing ''or'' between them.
+		by placing ''or'' between them.
 		For example, ''(update: slow) or (hover: none)''
 		matches if the device is slow to update the screen (such as an e-reader)
 		<em>or</em> the device has no hover capability,