Change FileReader.readAsText‘s 2nd argument name

Change from `label` to the more descriptive `encoding`[1].

[1]: https://developer.mozilla.org/en-US/docs/Web/API/FileReader/readAsText

Author: blixt

lib/lib.dom.d.ts

@@ -5322,7 +5322,7 @@ interface FileReader extends EventTarget {
     readAsArrayBuffer(blob: Blob): void;
     readAsBinaryString(blob: Blob): void;
     readAsDataURL(blob: Blob): void;
-    readAsText(blob: Blob, label?: string): void;
+    readAsText(blob: Blob, encoding?: string): void;
     readonly DONE: number;
     readonly EMPTY: number;
     readonly LOADING: number;