Add the pageref element

This instruction is useful if you want to get the number of the page
containing a specific bookmark.

src/file/paragraph/links/pageref.ts

@@ -0,0 +1,13 @@
+// See https://www.ecma-international.org/publications/standards/Ecma-376.htm (at Part 1, Page 1234)
+import { Begin, End } from "file/paragraph/run/field";
+import { Run } from "../run";
+import { PageRefFieldInstruction } from "./pageref-field-instruction";
+import type { IPageRefOptions } from "./pageref-properties";
+
+export class PageRef extends Run {
+    constructor(bookmarkId: string, options: IPageRefOptions = {}) {
+        super({
+            children: [new Begin(true), new PageRefFieldInstruction(bookmarkId, options), new End()],
+        });
+    }
+}