docs(my-ls): add the restriction to the os/exec package in the subject and audit

subjects/my-ls-1/README.md

@@ -22,6 +22,7 @@
 - Your project must be written in **Go**.
 - The code must respect the [**good practices**](../good-practices/README.md).
 - It is recommended to have **test files** for [unit testing](https://go.dev/doc/tutorial/add-a-test).
+- The use of the `os/exec` package is prohibited within the `my-ls` codebase.
 
 ### Allowed packages
 

subjects/my-ls-1/audit/README.md

@@ -2,6 +2,8 @@
 
 ###### Has the requirement for the allowed packages been respected?
 
+###### Can you confirm that the `os/exec` package was not used in this project?
+
 ##### Run both my-ls and the system command `ls` with no arguments.
 
 ###### Does it display the same files and/or folders in the same order?