add doc for cmd.execute

docs/cmd.rst

@@ -0,0 +1,16 @@
+Cmd
+-------
+
+.. function:: pydu.cmd.execute(cmd, wait=True, shell=True)
+
+    Execute cmd based on ``subprocess.Popen``.
+    If ``wait`` is True, ``execute`` will return the tuple of ``(returncode, stdout)``.
+    Note, ``stderr`` is redirected to ``stdout``. If ``wait`` is False, ``execute``
+    will return object of ``Popen``.
+    ``shell`` is same to parameter of ``Popen``.
+
+    >>> from pydu.cmd import execute
+    >>> execute('echo hello')
+    (0, b'hello\r\n')  # Python 3
+    >>> execute('echo hello', wait=False)
+    <subprocess.Popen at 0x22e4010f9e8>

docs/index.rst

@@ -21,6 +21,7 @@ Content
    :maxdepth: 1
 
    archive
+   cmd
    compat
    dict
    misc