Update explain.md

Fix spacing alignment issue.

Author: kohaiy

examples/src/docs/zh/ve-table/event-custom/explain.md

@@ -55,7 +55,7 @@ eventCustomOption: {
       contextmenu: (event) => {},
       mouseenter: (event) => {},
       mouseleave: (event) => {},
-       mousemove: (event) => {},
+      mousemove: (event) => {},
       mouseover: (event) => {},
       mousedown: (event) => {},
       mouseup: (event) => {},