clarification

nifty5/minimization/scipy_minimizer.py

@@ -151,7 +151,8 @@ class ScipyCG(Minimizer):
     """Returns a ScipyMinimizer object carrying out the conjugate gradient
     algorithm as implemented by SciPy.
 
-    This class is probably superfluous and can be removed.
+    This class is only intended for double-checking NIFTy's own conjugate
+    gradient implementation and should not be used otherwise.
     """
     def __init__(self, tol, maxiter):
         if not dobj.is_numpy():