feature: add support to add mutiple sections to the document inc. headers and footers

- write missing tests

src/file/header/header.ts

@@ -6,8 +6,10 @@ import { Table } from "../table";
 import { HeaderAttributes } from "./header-attributes";
 
 export class Header extends XmlComponent {
-    constructor() {
+    private refId: number;
+    constructor(referenceNumber: number) {
         super("w:hdr");
+        this.refId = referenceNumber;
         this.root.push(
             new HeaderAttributes({
                 wpc: "http://schemas.microsoft.com/office/word/2010/wordprocessingCanvas",
@@ -30,6 +32,10 @@ export class Header extends XmlComponent {
         );
     }
 
+    get referenceId() {
+        return this.refId;
+    }
+
     public addParagraph(paragraph: Paragraph): void {
         this.root.push(paragraph);
     }