Fix typo.

object-storage.md

 # Object Storage
 
-All relevant documentation for Object Storage services could be found at [du.cesnet.cz](https://du.cesnet.cz/en/navody/object_storage/start)
+Detail documentation for Object Storage services could be found at [du.cesnet.cz](https://du.cesnet.cz/en/navody/object_storage/start)