[css-animations-2][editorial] Improve paragaph about instantaneous animations.

Author: fantasai

css-animations-2/Overview.bs

@@ -449,18 +449,18 @@ Declaring Animations</h2>
   </dl>
 
   If the [=used value|used=] 'animation-duration' is ''0s'',
-  the keyframes of the animation have no effect,
-  but the animation itself still occurs instantaneously.
-  Specifically, start and end events are fired;
-  if 'animation-fill-mode' is set to ''backwards'' or ''both'',
-  the first frame of the animation,
-  as defined by 'animation-direction',
-  will be displayed during the 'animation-delay'.
-  After the 'animation-delay' the last frame of the animation,
-  as defined by 'animation-direction',
-  will be displayed if 'animation-fill-mode' is set to ''forwards'' or ''both''.
-  If 'animation-fill-mode' is set to ''animation-fill-mode/none''
-  the animation will have no visible effect.
+  the animation itself still occurs (instantaneously).
+  The animation’s start and end events are still fired.
+  If 'animation-fill-mode' is set to ''backwards'' or ''both'',
+  the first frame of the animation
+  (as defined by 'animation-direction')
+  will be displayed during the 'animation-delay';
+  and if 'animation-fill-mode' is set to ''forwards'' or ''both'',
+  the last frame of the animation
+  (as defined by 'animation-direction')
+  will be displayed after the 'animation-delay'.
+  However, if 'animation-fill-mode' is set to ''animation-fill-mode/none''
+  the keyframes of the animation animation will have no noticeable effect.
 
 ## The 'animation-timing-function' property ## {#animation-timing-function}