refactor: add message at the end of command

tutor/commands/config.py

@@ -265,7 +265,9 @@ def edit(context: Context) -> None:
     config_file = tutor_config.config_path(context.root)
 
     if not os.path.isfile(config_file):
-        raise exceptions.TutorError(f"Missing config file at {config_file}. Have you run 'tutor local launch' yet?")
+        raise exceptions.TutorError(
+            f"Missing config file at {config_file}. Have you run 'tutor local launch' yet?"
+        )
 
     open_cmd = None
 
@@ -278,9 +280,14 @@ def edit(context: Context) -> None:
         # The second argument "" just means "don't give the window a custom title".
         open_cmd = ["start", '""', config_file]
     else:
-        raise exceptions.TutorError(f"Failed to find utility to launch an editor.")
+        raise exceptions.TutorError(
+            f"Failed to find utility to launch an editor. Edit {config_file} with the editor of your choice."
+        )
 
     subprocess.call(open_cmd)
+    click.echo(
+        "Remember to run 'tutor config save' after editing, to apply the changes to your environment."
+    )
 
 
 config_command.add_command(save)