feature: add support to add mutiple sections to the document inc. headers and footers

- write missing tests

src/file/document/body/section-properties/index.ts

@@ -0,0 +1,5 @@
+export * from "./section-properties";
+export * from "./footer-reference";
+export * from "./header-reference";
+export * from "./page-size";
+export * from "./page-number";