Improved clarity

readme.md

@@ -67,7 +67,7 @@ await configure({
 > When configuring a mount point, you can pass in
 > 1. A string that maps to a built-in backend
 > 2. A `Backend` object, if the backend has no required options
-> 3. An object that has a `backend` property which is a `Backend` or a string that maps to a built-in backend and the options accepted by the backend
+> 3. An object that has the options accepted by the backend and a `backend` property which is (1) or (2)
 
 Here is an example that mounts the `Storage` backend from `@browserfs/dom` on `/`: