Adapted README.md to release 3.0.0

Author: Daniel-Schroeter

README.md

@@ -11,7 +11,7 @@ Function | Description | Note
 local_course_add_new_course_module_url |Add course module URL |
 local_course_add_new_course_module_resource | Add course module Resource | File needs to be uploaded with "/webservice/upload.php" web service call.
 local_course_add_new_course_module_directory | Add course modul Folder | Files need to be uploaded with "/webservice/upload.php" web service call.
-local_course_add_files_to_directory | Add files to folder | Work in progress - not working yet
+local_course_add_files_to_directory | Add files to existing folders | Files need to be uploaded with "/webservice/upload.php" web service call; Since version 3.0.0
 local_course_move_module_to_specific_position | Move a module to a dedicated position |
 local_course_add_new_section | Create and position a new course section | Since version 2.0.0