[css-images-3][css-images-4] Spell check.

Author: dbaron

css-images-3/Overview.bs

@@ -182,7 +182,7 @@ Image References: the ''url()'' notation {#url-notation}
 	An <dfn export for=CSS>ambiguous image URL</dfn> is
 	a <<url>> value that can be interpreted
 	as either an <<image>> or an element reference.
-	If an [=ambigous image URL=] is a [[css-values-3#local-urls|fragment-only URL]],
+	If an [=ambiguous image URL=] is a [[css-values-3#local-urls|fragment-only URL]],
 	then it must be treated as an element reference.
 	Otherwise, if the [=ambiguous image URL=] has a fragment
 	that references an element in the resource
@@ -935,7 +935,7 @@ Coloring the Gradient Line</h4>
 	If the hint is placed anywhere else,
 	it produces a smooth exponential curve
 	between the surrounding color stops,
-	with the “halfway color” occuring exactly where the hint specifies.
+	with the “halfway color” occurring exactly where the hint specifies.
 
 	Issue: Add a visual example of a color hint being used.
 

css-images-4/Overview.bs

@@ -1517,7 +1517,7 @@ Coloring the Gradient Line</h4>
 	If the hint is placed anywhere else,
 	it produces a smooth exponential curve
 	between the surrounding color stops,
-	with the “halfway color” occuring exactly where the hint specifies.
+	with the “halfway color” occurring exactly where the hint specifies.
 
 	Issue: Add a visual example of a color hint being used.