Document how to use ZServer instead of WSGI.

docs/INSTALL-buildout.rst

@@ -68,6 +68,15 @@ On Linux, this can be done as follows::
 Creating a Zope instance
 ::::::::::::::::::::::::
 
+.. attention::
+
+  The following steps describe how to install a WSGI based Zope instance.
+  If you want/have to use ZServer instead of WSGI (Python 2 only!) follow
+  the documentation `Creating a Zope instance for Zope 2.13`_, as it did not have
+  changed since that version.
+
+.. _`Creating a Zope instance for Zope 2.13` : http://zope.readthedocs.io/en/2.13/INSTALL-buildout.html#creating-a-zope-instance
+
 Once you've installed Zope, you will need to create an "instance
 home". This is a directory that contains configuration and data for a
 Zope server process.  The instance home is created using the

docs/INSTALL-virtualenv.rst

@@ -36,6 +36,16 @@ version in the URL, replacing 4.0b1 in the example below:
 Creating a Zope instance
 ------------------------
 
+.. attention::
+
+  The following steps describe how to install a WSGI based Zope instance.
+  If you want/have to use ZServer instead of WSGI (Python 2 only!) follow
+  the documentation `Creating a Zope instance for Zope 2.13`_, as it did not have
+  changed since that version.
+
+.. _`Creating a Zope instance for Zope 2.13` : http://zope.readthedocs.io/en/2.13/INSTALL-virtualenv.html#creating-a-zope-instance
+
+
 Once you've installed Zope, you will need to create an "instance
 home". This is a directory that contains configuration and data for a
 Zope server process.  The instance home is created using the