diff --git a/Doc/using/cmdline.rst b/Doc/using/cmdline.rst
index 3481d5b..9eecba6 100644
--- a/Doc/using/cmdline.rst
+++ b/Doc/using/cmdline.rst
@@ -78,6 +78,12 @@
    the implementation may not always enforce this (e.g. it may allow you to
    use a name that includes a hyphen).
 
+   Package names are also permitted. When a package name is supplied instead
+   of a normal module, the interpreter will execute ``<pkg>.__main__`` as
+   the main module. This behaviour is deliberately similar to the handling
+   of directories and zipfiles that are passed to the interpreter as the
+   script argument.
+
    .. note::
 
       This option cannot be used with builtin modules and extension modules
@@ -97,11 +103,14 @@
 
    .. seealso::
       :func:`runpy.run_module`
-         The actual implementation of this feature.
+         Equivalent functionality directly available to Python code
 
       :pep:`338` -- Executing modules as scripts
 
 
+   .. versionchanged:: 3.1
+      Supply the package name to run a ``__main__`` submodule.
+
 .. describe:: -
 
    Read commands from standard input (:data:`sys.stdin`).  If standard input is