Change docx folder to more appropriate "file" folder

src/file/paragraph/run/tab.spec.ts

@@ -0,0 +1,19 @@
+import { assert } from "chai";
+
+import { Utility } from "../../../tests/utility";
+import { Tab } from "./tab";
+
+describe("Tab", () => {
+    let tab: Tab;
+
+    beforeEach(() => {
+        tab = new Tab();
+    });
+
+    describe("#constructor()", () => {
+        it("should create a Tab with correct root key", () => {
+            const newJson = Utility.jsonify(tab);
+            assert.equal(newJson.rootKey, "w:tab");
+        });
+    });
+});