Make Paragraph declaritive

src/file/paragraph/formatting/style.ts

@@ -1,5 +1,15 @@
 import { Attributes, XmlComponent } from "file/xml-components";
 
+export enum HeadingLevel {
+    HEADING_1 = "Heading1",
+    HEADING_2 = "Heading2",
+    HEADING_3 = "Heading3",
+    HEADING_4 = "Heading4",
+    HEADING_5 = "Heading5",
+    HEADING_6 = "Heading6",
+    TITLE = "Title",
+}
+
 export class Style extends XmlComponent {
     public readonly styleId: string;