docs/ustruct: There's no complete "struct" module, only "ustruct" subset.

"ustruct" is good example of micro-ified module, so rather should belong
to the corresponding list.

docs/library/struct.rst

@@ -1,25 +0,0 @@
-:mod:`struct` -- pack and unpack primitive data types
-=====================================================
-
-.. module:: struct
-   :synopsis: pack and unpack primitive data types
-
-See `Python struct <https://docs.python.org/3/library/struct.html>`_ for more
-information.
-
-Functions
----------
-
-.. function:: calcsize(fmt)
-
-   Return the number of bytes needed to store the given ``fmt``.
-
-.. function:: pack(fmt, v1, v2, ...)
-
-   Pack the values ``v1``, ``v2``, ... according to the format string ``fmt``.
-   The return value is a bytes object encoding the values.
-
-.. function:: unpack(fmt, data)
-
-   Unpack from the ``data`` according to the format string ``fmt``.
-   The return value is a tuple of the unpacked values.