[css-round-display] Make polar-distance animatable as an angle (ACTION-710: https://www.w3.org/Style/CSS/Tracker/actions/710)(2)

Author: hyojinLGE

css-round-display/Overview.bs

@@ -310,7 +310,7 @@ The 'polar-distance' property specifies the distance from the center of the pare
     Media: visual
     Inherited: no
     Percentages: relative to distance from center to edge of containing block
-    Animatable: as <angle>
+    Animatable: as <a href="http://www.w3.org/TR/css3-transitions/#animtype-lpcalc">length, percentage, or calc</a>
 </pre>
 
 <div class='example'>