Fix doc links

CL: Fix doc links

PUBLISHED_FROM=78d16eb888782fc0289b8d29e9da17fe096f2cfb

Author: cpq

README.md

@@ -5,5 +5,4 @@ Engine](https://github.com/cesanta/mjs).
 
 Apart from adding the mJS itself, the library creates a global instance of it
 (available via `mgos_mjs_get_global()`), and also brings a number of
-mgos-specific
-[JavaScript API files](https://mongoose-os.com/docs/reference/api.html#mjs).
+mgos-specific API files, see `fs` directory.