remove matplotlib argument to IPython in intro

doc/users/image_tutorial.rst

@@ -12,12 +12,11 @@ Startup commands
 
 First, let's start IPython.  It is a most excellent enhancement to the
 standard Python prompt, and it ties in especially well with
-Matplotlib.  The easy way to enter IPython at a shell::
+Matplotlib.  Start IPython either at a shell, or the IPython Notebook now.
 
-    $ipython --matplotlib
-
-If you've already started IPython and forgot the --matplotlib part, no
-problem; just type %matplotlib at your IPython prompt.  There's more
+With IPython started, we now need to connect to a GUI event loop.  This
+tells IPython where (and how) to display plots.  To connect to a GUI
+loop, execute the **%matplotlib** magic at your IPython prompt.  There's more
 detail on exactly what this does at `IPython's documentation on GUI
 event loops
 <http://ipython.org/ipython-doc/2/interactive/reference.html#gui-event-loop-support>`_.