[css-values-3][css-values-4] Replace references to single-timing-function with timing-function

See w3c#2028 and 720c191.

Author: birtles

css-values-3/Overview.bs

@@ -427,7 +427,7 @@ Author-defined Identifiers: the <<custom-ident>> type</h3>
 		For example, the shorthand declaration ''animation: ease-in ease-out''
 		is equivalent to the longhand declarations
 		''animation-timing-function: ease-in; animation-name: ease-out;''.
-		''ease-in'' is claimed by the <<single-timing-function>> production belonging to 'animation-timing-function',
+		''ease-in'' is claimed by the <<timing-function>> production belonging to 'animation-timing-function',
 		leaving ''ease-out'' to be claimed by the <<custom-ident>> production belonging to 'animation-name'.
 	</div>
 

css-values-4/Overview.bs

@@ -417,7 +417,7 @@ Author-defined Identifiers: the <<custom-ident>> type</h3>
 		For example, the shorthand declaration ''animation: ease-in ease-out''
 		is equivalent to the longhand declarations
 		''animation-timing-function: ease-in; animation-name: ease-out;''.
-		''ease-in'' is claimed by the <<single-timing-function>> production belonging to 'animation-timing-function',
+		''ease-in'' is claimed by the <<timing-function>> production belonging to 'animation-timing-function',
 		leaving ''ease-out'' to be claimed by the <<custom-ident>> production belonging to 'animation-name'.
 	</div>