Move the 3k reST doc tree in place.

Doc/library/unix.rst

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+
+.. _unix:
+
+**********************
+Unix Specific Services
+**********************
+
+The modules described in this chapter provide interfaces to features that are
+unique to the Unix operating system, or in some cases to some or many variants
+of it.  Here's an overview:
+
+
+.. toctree::
+
+   posix.rst
+   pwd.rst
+   spwd.rst
+   grp.rst
+   crypt.rst
+   dl.rst
+   termios.rst
+   tty.rst
+   pty.rst
+   fcntl.rst
+   pipes.rst
+   resource.rst
+   nis.rst
+   syslog.rst
+   commands.rst