Update the URLs about CLS

Change-Id: Ic329268bc74bd59a9bd52211563d24613202aa85
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2266412Reviewed-by: Kinuko Yasuda <kinuko@chromium.org>
Commit-Queue: Hajime Hoshi <hajimehoshi@chromium.org>
Cr-Commit-Position: refs/heads/master@{#782866}

components/page_load_metrics/common/page_load_metrics.mojom

@@ -267,11 +267,11 @@ struct ResourceDataUpdate {
 
 // Metrics about how a RenderFrame rendered since the last UpdateTiming call.
 struct FrameRenderDataUpdate {
-  // How much visible elements in the frame shifted (bit.ly/lsm-explainer) since
+  // How much visible elements in the frame shifted (https://bit.ly/3fQz29y) since
   // the last timing update.
   float layout_shift_delta;
 
-  // How much visible elements in the frame shifted (bit.ly/lsm-explainer),
+  // How much visible elements in the frame shifted (https://bit.ly/3fQz29y),
   // before a user input or document scroll, since the last timing update.
   float layout_shift_delta_before_input_or_scroll;