[css-inline-3] Fix typo -- ingoring --> ignoring (w3c#6216)

Author: twilco

css-inline-3/Overview.bs

@@ -223,7 +223,7 @@ Layout Within Line Boxes</h3>
 				For the [=root inline box=],
 				and for [=inline boxes=] with ''text-edge: leading'':
 				this derived from their used 'line-height',
-				ingoring any [=margin=]/[=border=]/[=padding=]
+				ignoring any [=margin=]/[=border=]/[=padding=]
 				see [[#inline-height]].
 
 			<li>