Create section properties section

src/file/document/body/section-properties/columns/columns-attributes.ts

@@ -0,0 +1,11 @@
+import { XmlAttributeComponent } from "file/xml-components";
+
+export interface IColumnsAttributes {
+    space?: number;
+}
+
+export class ColumnsAttributes extends XmlAttributeComponent<IColumnsAttributes> {
+    protected xmlKeys = {
+        space: "w:space",
+    };
+}