fix missing link

Author: lohanidamodar

README.md

@@ -68,8 +68,6 @@ if ($user->isAdmin()) {
 - ✅ Code organization and encapsulation
 - ✅ Fully backwards compatible
 
-For complete documentation, see [docs/custom-document-types.md](docs/custom-document-types.md).
-
 ### Reserved Attributes
 
 - `$id` - the document unique ID, you can set your own custom ID or a random UID will be generated by the library.