Use a working example for the aux reader (#52)

This depends on MDAnalysis/mdanalysis#1290 being merged!

_posts/2017-11-11-release-0.16.0.md

@@ -57,14 +57,18 @@ auxiliary data corresponding to the current time step.
 
 {% highlight python %}
 import MDAnalysis as mda
+from MDAnalysisTests.datafiles import PDB_sub_sol, XTC_sub_sol, XVG_BZ2
 
 # Create your universe as usual
-universe = mda.Universe(SIMULATION)
-# Attach an auxiliary time serie with the name `pull_force`
-universe.trajectory.add_auxiliaty('pull_force', 'md_f.xvg')
+universe = mda.Universe(PDB_sub_sol, XTC_sub_sol)
+# Attach an auxiliary time serie with the name `forces`
+# In this example, the XVG file contains the force that applies to each atom.
+universe.trajectory.add_auxiliary('forces', XVG_BZ2)
 # Itarete through your trajectory, the time serie is kept in sync
 for time_step in universe.trajectory:
-    print(time_step.aux.pull_force)
+    print(time_step.aux.forces)
+# The first element of each array is the time in picoseconds.
+# The next elements are the other columns of the XVG file.
 {% endhighlight %}
 
 @fiona-naugthon worked at offering several convenient way to iterate through your