title: How to insert text outside a plot
body: <p>I have the following plot (with 3 rows and 4 columns):</p>
  
  <pre><code>f, ((ax1, ax2, ax3, ax4), (ax5, ax6, ax7, ax8), (ax9, ax10, ax11, ax12)) = plt.subplots(3,   4, sharex = 'col', sharey = 'row')
  ax1.set_title('column1')
  ax1.plot([x], [y])
  ax5.plot([x1],[y1])
  ax9.plot([x2],[y2])
  ax2.set_title('column2')
  ax2.plot([x3],[x4])
  ax6.plot([x5],[x6])
  .....
  </code></pre>
  
  <p>How is it possible to insert text outside the plot window? For each row I would like to write a sentence on the right end side of the plot.</p>