Test descriptions

tests/proto/helloworld.md

@@ -0,0 +1,8 @@
+`py helloworld.py 42 abc`
+
+```py
+print(args)
+for _ in range(2):
+  print("Hello world!")
+print("Привет мир!")
+```

tests/proto/repl2p2.md

@@ -0,0 +1,7 @@
+`py`
+
+```py
+>>> 2+2
+4
+>>> (ctrl+D)
+```

tests/proto/replterm.md

@@ -0,0 +1,8 @@
+`py`
+
+```py
+>>> 'a' * 5
+'aaaaa'
+>>> (ctrl+C)
+interrupted
+```