Update loading.md

fix Events typo:  onloading -> loading
diff --git a/source/references/components/loading.md b/source/references/components/loading.md
index 25b0971..c152f46 100644
--- a/source/references/components/loading.md
+++ b/source/references/components/loading.md
@@ -94,7 +94,7 @@
 
 ## Events
 
-### `onloading`
+### `loading`
 
  - Triggered when the scroller or list is pulled up.