[web-animations-1] DD indent for Bikeshed (#5953)

Author: nschonni

web-animations-1/Overview.bs

@@ -1180,7 +1180,7 @@ as CSS Animations [[CSS-ANIMATIONS-1]].
     :   If |animation|'s [=effective playback rate=] = 0 and |animation|'s
         [=current time=] is [=unresolved=],
 
-        ::  Set <var>seek time</var> to zero.
+    ::  Set <var>seek time</var> to zero.
 
     </div>