Change docx folder to more appropriate "file" folder

src/file/index.ts

@@ -0,0 +1,8 @@
+export * from "./document";
+export * from "./paragraph";
+export * from "./table";
+export * from "./file";
+export * from "./numbering";
+export * from "./media";
+export * from "./drawing";
+export * from "./styles";