Merge pull request #1963 from jhlegarreta/FixLiFEDocstring

DOC: Fix parameter docstring in LiFE tracking script

dipy/tracking/life.py

@@ -218,7 +218,7 @@ def __init__(self, gtab, evals=[0.001, 0, 0], sphere=None):
         evals : list of 3 items
             The eigenvalues of the canonical tensor to use in calculating the
             signal.
-        n_points : `dipy.core.Sphere` class instance
+        sphere : `dipy.core.Sphere` class instance
             The discrete sphere to use as an approximation for the continuous
             sphere on which the signal is represented. If integer - we will use
             an instance of one of the symmetric spheres cached in