[css-ui-4] Remove issue which is no longer relevant

Author: frivoal

css-ui-4/Overview.bs

@@ -174,10 +174,6 @@ textarea {
 		Text area
 		with color-alternating caret<span style="border-right: 2px solid blue;animation: caret-alternate 2s step-end infinite;"></span>
 	</div>
-
-	Issue: This example does not work
-	because caret-color is currently marked as not annimatable.
-	This is probably wrong.
 </div>