Add demo20 table border styles

demo/demo20.js

@@ -0,0 +1,17 @@
+const docx = require("../build");
+
+var doc = new docx.Document();
+
+const table = doc.createTable(4, 4);
+table
+    .getCell(2, 2)
+    .addContent(new docx.Paragraph("Hello"))
+    .cellProperties.borders.addTopBorder(docx.BorderStyle.DASH_DOT_STROKED, 3, "red")
+    .addBottomBorder(docx.BorderStyle.DOUBLE, 3, "blue")
+    .addStartBorder(docx.BorderStyle.DOT_DOT_DASH, 3, "green")
+    .addEndBorder(docx.BorderStyle.DOT_DOT_DASH, 3, "#ff8000");
+
+var exporter = new docx.LocalPacker(doc);
+exporter.pack("My Document");
+
+console.log("Document created successfully at project root!");