Use python3 as the canonical command name course-wide (#104) (#105)

modules/10-reviewing-code-you-didnt-write/lab/start/cli.py

@@ -1,9 +1,9 @@
 """Tiny command-line front end for the demo task app.
 
 Run it:
-    python cli.py add "write the lesson"
-    python cli.py list
-    python cli.py done 0
+    python3 cli.py add "write the lesson"
+    python3 cli.py list
+    python3 cli.py done 0
 
 State is kept in tasks.json next to this file. The `done` command turns a bad index into a
 clean error message and a non-zero exit code; note that behavior before you review the AI
@@ -33,7 +33,7 @@ def save(tlist: TaskList) -> None:
 def main(argv: list[str]) -> int:
     tlist = load()
     if not argv:
-        print("usage: python cli.py [add <title> | list | done <index>]")
+        print("usage: python3 cli.py [add <title> | list | done <index>]")
         return 1
 
     command = argv[0]