[css-display-3] Tweak text content example per Amelia’s suggestions. w3c#3302

Author: fantasai

css-display-3/Overview.bs

@@ -1275,7 +1275,7 @@ SVG Elements {#unbox-svg}
 		its child text content and elements are no longer valid.
 		For that reason, ''display: contents'' on <{text}>
 		prevents the entire text element from being rendered.
-		In contrast, any content inside a <{tspan}> or <{textPath}>
+		In contrast, any valid content inside a <{tspan}> or <{textPath}>
 		is also valid content inside the parent text formatting context,
 		so the hoisting behavior applies for these elements.
 
@@ -1287,8 +1287,6 @@ SVG Elements {#unbox-svg}
 		that is an invalid change of rendering context.
 		Never-rendered container elements therefore cannot be "un-boxed"
 		by ''display: contents''.
-		(Also, authors cannot override the 'display' property on these elements:
-		it is forced to ''none'' by an ''!important'' user agent style rule.)
 	</div>
 
 	When an element is stripped from the formatting tree,