Minor documentation modernizations

This fixes various little outdatednesses throughout the installation,
examples and guided tour.

doc/examples.rst

@@ -21,17 +21,17 @@ Client
 .. literalinclude:: ../clientGET.py
    :language: python
    :linenos:
-   :lines: 15-
+   :lines: 11-
 
 .. literalinclude:: ../clientPUT.py
    :language: python
    :linenos:
-   :lines: 15-
+   :lines: 11-
 
 Server
 ------
 
 .. literalinclude:: ../server.py
    :language: python
    :linenos:
-   :lines: 15-
+   :lines: 11-

doc/guidedtour.rst

@@ -54,14 +54,12 @@ It tells that there is a resource at the path ``/time`` that has the ``obs``\
 ervable attribute, a resource at the path ``/.well-known/core``, and more at
 ``/other/...`` and ``/whoami``.
 
-.. note:: Getting "5.00 Internal Server Error" instead, all lines in a single
+.. note:: Getting all lines in a single
     row or no color? Then there are third party modules missing. Run ``python3
     -m aiocoap.cli.defaults`` to see which they are, or just go back to the
     :ref:`installation step<installation-development>` and make sure to include
     the "``[all]``" part.
 
-.. _`link_header module`: https://pypi.python.org/pypi/LinkHeader
-
 .. note:: There can be a "(No newline at end of message)" line below your
     output. This just makes sure your prompt does not start in the middle of
     the screen. I'll just ignore that.
@@ -148,6 +146,7 @@ session, as support for the asynchronous shell is always available there.
 
 ::
 
+    >>> from aiocoap import *
     >>> protocol = await Context.create_client_context()
     >>> msg = Message(code=GET, uri="coap://localhost/other/separate")
     >>> response = await protocol.request(msg).response

doc/installation.rst

@@ -20,13 +20,6 @@ aiocoap. This is done using a simple::
 
 (In some cases, the program is called ``pip`` only).
 
-If ``pip3`` is not available on your platform, you can manually download and
-unpack the latest ``.tar.gz`` file from the `Python package index`_ and run
-
-::
-
-    $ ./setup.py install
-
 
 .. _installation-development:
 
@@ -86,11 +79,6 @@ installation.
 
 The extras currently supported are:
 
-* ``linkheader``: Needed for generating and parsing files in RFC6690_ link
-  format, eg. ``.well-known/core`` files. Running or interacting with a
-  Resource Directory is impossible without this module, as are many other
-  discovery steps that applications will want to do.
-
 * ``oscore``: Required for the :mod:`aiocoap.transports.oscore` transport.
 
 * ``tinydtls``: Required for using CoAP over DTLS.
@@ -103,6 +91,10 @@ The extras currently supported are:
 * ``docs``: Installs tools needed to build the documentation (not part of
   ``all``).
 
+* ``linkheader``: Originally needed for generating and parsing files in
+  RFC6690_ link format, eg. ``.well-known/core`` files. This extra does not
+  contain any external dependencies, but was left in place for compatibility.
+
 Which libraries and versions are pulled in by this exactly is documented in the
 ``setup.py`` file.