fix: broken relative link when used as submodule

Author: songlim327

docs/quick-start/sales/sales-invoice/intro.md

@@ -19,4 +19,4 @@ dataEntryList = {[
 ]}
 />
 
-[Click to learn more about E-Invoice](/quick-start/e-invoice)
+[Click to learn more about E-Invoice](../e-invoice)