Documentation updates.

docs/examples/mesh/plot_nodes.py

@@ -0,0 +1,13 @@
+import numpy as np
+import matplotlib.pyplot as plt
+from SimPEG import TensorMesh
+
+x0 = np.zeros(2)
+h1 = np.linspace(.1,.5,3)
+h2 = np.linspace(.1,.5,5)
+M = TensorMesh([h1,h2],x0)
+M.plotGrid()
+plt.hold()
+plt.plot(M.gridN[:,0], M.gridN[:,1], 'ks', markersize=10)
+plt.show()
+