fix: fix markdown highlight

Author: Xin Nie

2-ui/5-loading/01-onload-ondomcontentloaded/article.md

@@ -277,7 +277,7 @@ Page load events:
   - Images and other resources may also still continue loading.
 - The `load` event on `window` triggers when the page and all resources are loaded. We rarely use it, because there's usually no need to wait for so long.
 - The `beforeunload` event on `window` triggers when the user wants to leave the page. If we cancel the event, browser asks whether the user really wants to leave (e.g we have unsaved changes).
-- `The unload` event on `window` triggers when the user is finally leaving, in the handler we can only do simple things that do not involve delays or asking a user. Because of that limitation, it's rarely used. We can send out a network request with `navigator.sendBeacon`.
+- The `unload` event on `window` triggers when the user is finally leaving, in the handler we can only do simple things that do not involve delays or asking a user. Because of that limitation, it's rarely used. We can send out a network request with `navigator.sendBeacon`.
 - `document.readyState` is the current state of the document, changes can be tracked in the `readystatechange` event:
   - `loading` -- the document is loading.
   - `interactive` -- the document is parsed, happens at about the same time as `DOMContentLoaded`, but before it.