Add GitHubHandler class

packages/content-handler/src/websites/github-handler.ts

@@ -0,0 +1,23 @@
+import { ContentHandler } from '../content-handler'
+
+export class GitHubHandler extends ContentHandler {
+  constructor() {
+    super()
+    this.name = 'github'
+  }
+
+  shouldPreParse(url: string, dom: Document): boolean {
+    return new URL(url).hostname.endsWith('github.com')
+  }
+
+  async preParse(url: string, dom: Document): Promise<Document> {
+    const body = dom.querySelector('body')
+    const article = dom.querySelector('article')
+
+    if (body && article) {
+      body?.replaceChildren(article)
+    }
+
+    return Promise.resolve(dom)
+  }
+}