[css-tables] Made small editorial change for authors stated in issue #508

Author: Greg Whitworth

css-tables-3/Overview.bs

@@ -191,9 +191,9 @@ spec:css22; type:property; text:display
 	
 
 	
-		Authors must not assign a display type from the previous list to replaced elements (like input fields or images).
+		Authors should not assign a display type from the previous list to replaced elements (eg: input fields or images).
 		When the 'display' property of a replaced element computes to one of these values,
-			it is handled instead as would
+			it is handled instead as though the author had declared
 			inline (for inline-table, table-cell, table-column) or
 			block (for all other values).
 		Whitespace collapsing and box generation must happen around those replaced elements