Change docx folder to more appropriate "file" folder

src/file/document/body/body.ts

@@ -0,0 +1,12 @@
+import { XmlComponent } from "../../xml-components";
+
+export class Body extends XmlComponent {
+
+    constructor() {
+        super("w:body");
+    }
+
+    public push(component: XmlComponent): void {
+        this.root.push(component);
+    }
+}