Remove wrong usage of :option:

From http://www.sphinx-doc.org/en/stable/domains.html#directive-option:

  > The directive will create cross-reference targets for the given options,
  > referencable by option (in the example case, you’d use something like
  > :option:`dest_dir`, :option:`-m`, or :option:`--module`).

I don't think we're intending here to create cross references,
we simply want to render it nicely.

So just use code formatting instead.

This gets rid of the last build warnings.

docs/shipping/freezing.rst

@@ -60,7 +60,7 @@ py2app      no      no    yes  yes      MIT     no            yes            yes
 .. note::
     All solutions need MS Visual C++ dll to be installed on target machine, except py2app.
     Only Pyinstaller makes self-executable exe that bundles the dll when
-    passing :option:`--onefile` to :file:`Configure.py`.
+    passing ``--onefile`` to :file:`Configure.py`.
 
 Windows
 -------

docs/shipping/packaging.rst

@@ -101,7 +101,7 @@ pypiserver
 `Pypiserver <https://pypi.python.org/pypi/pypiserver>`_ is a minimal PyPI
 compatible server.  It can be used to serve a set of packages to easy_install
 or pip.  It includes helpful features like an administrative command
-(:option:`-U`) which will update all its packages to their latest versions
+(``-U``) which will update all its packages to their latest versions
 found on PyPI.