Also clarify delay units. Fixes #4707

Author: kevinpschaaf

lib/elements/dom-repeat.html

@@ -218,7 +218,7 @@
 
         /**
          * When using a `filter` or `sort` function, the `delay` property
-         * determines a debounce time after a change to observed item
+         * determines a debounce time in ms after a change to observed item
          * properties that must pass before the filter or sort is re-run.
          * This is useful in rate-limiting shuffling of the view when
          * item changes may be frequent.