fix link in 4. and 5.

4_unix_file_system.md

@@ -222,4 +222,4 @@ mount
 
 Find which disk is mounted at the root of the file tree.
 
-[That’s all for the Unix file system, we will come back to it from time to time but for now you can head to the next section.](http://perso.ens-lyon.fr/laurent.modolo/unix/4_users_and_rights.html)
\ No newline at end of file
+[That’s all for the Unix file system, we will come back to it from time to time but for now you can head to the next section.](http://perso.ens-lyon.fr/laurent.modolo/unix/5_users_and_rights.html)
\ No newline at end of file

5_users_and_rights.md

@@ -5,7 +5,7 @@ title: Users and rights
 
 # Users and rights
 
-[![cc_by_sa](/Users/laurent/Documents/formations/2020_08_UNIX/img/cc_by_sa.png)](http://creativecommons.org/licenses/by-sa/4.0/)
+[![cc_by_sa](./img/cc_by_sa.png)](http://creativecommons.org/licenses/by-sa/4.0/)
 
 Objective: Understand how rights works in GNU/Linux