Updated docs to reflect renaming of some tools scripts.

README.rst

@@ -182,7 +182,7 @@ When the simulation is complete you can plot the A-scan using:
 
 .. code-block:: none
 
-    python -m tools.plot_Ascan_hdf5 user_models/cylinder_Ascan_2D.out
+    python -m tools.plot_Ascan user_models/cylinder_Ascan_2D.out
 
 Optional command line arguments
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