Update Dragonfly's latest documentation

Re: #389.

The latest documentation and GitHub README now recommend installing
with 'pip install dragonfly2', for the moment.  Release candidates
for version 1.0.0 are also now mentioned.

README.rst

@@ -140,7 +140,18 @@ pip:
 
 .. code:: shell
 
-    pip install dragonfly
+    pip install dragonfly2
+
+If you wish to install the latest release candidate for version 1.0.0,
+please run the following command instead:
+
+.. code:: shell
+
+    pip install dragonfly2==1.0.0-rc2
+
+These versions are more up-to-date and have fewer requirements.  The
+documentation for them is available at `Read the Docs (latest)
+<http://dragonfly2.readthedocs.org/en/latest/>`_.
 
 If you are installing this on Linux, you will also need to install the
 `wmctrl <https://www.freedesktop.org/wiki/Software/wmctrl/>`__, `xdotool

documentation/installation.txt

@@ -47,12 +47,24 @@ that the Wayland user switch to X11.
 
 Installation of Dragonfly
 ----------------------------------------------------------------------------
+
 Dragonfly is a Python package. It can be installed as *dragonfly* using
 pip:
 
 .. code:: shell
 
-    pip install dragonfly
+    pip install dragonfly2
+
+If you wish to install the latest release candidate for version 1.0.0,
+please run the following command instead:
+
+.. code:: shell
+
+    pip install dragonfly2==1.0.0-rc2
+
+These versions are more up-to-date and have fewer requirements.  The
+documentation for them is available at `Read the Docs (latest)
+<http://dragonfly2.readthedocs.org/en/latest/>`_.
 
 Dragonfly can also be installed by cloning this repository or
 downloading it from `the releases