fix demos

demo/48-vertical-align.ts

@@ -1,13 +1,13 @@
 // Example of making content of section vertically aligned
 // Import from 'docx' rather than '../build' if you install from npm
 import * as fs from "fs";
-import { Document, Packer, Paragraph, SectionVerticalAlignValue, TextRun } from "../build";
+import { Document, Packer, Paragraph, VerticalAlign, TextRun } from "../build";
 
 const doc = new Document({
     sections: [
         {
             properties: {
-                verticalAlign: SectionVerticalAlignValue.CENTER,
+                verticalAlign: VerticalAlign.CENTER,
             },
             children: [
                 new Paragraph({