refactor: Move transcript logic to MediaInfo (#511)

* refactor: Move transcript logic to `MediaInfo`

+ Add support for retrieving different languages.

* docs: Update and add examples

src/parser/classes/TranscriptSectionHeader.ts

@@ -0,0 +1,18 @@
+import { YTNode } from '../helpers.js';
+import type { RawNode } from '../index.js';
+import Text from './misc/Text.js';
+
+export default class TranscriptSectionHeader extends YTNode {
+  static type = 'TranscriptSectionHeader';
+
+  start_ms: string;
+  end_ms: string;
+  snippet: Text;
+
+  constructor(data: RawNode) {
+    super();
+    this.start_ms = data.startMs;
+    this.end_ms = data.endMs;
+    this.snippet = new Text(data.snippet);
+  }
+}