docstring typo

Author: John Halloran

src/diffpy/snmf/snmf_class.py

@@ -48,10 +48,10 @@ def __init__(
             The stretching factor that influences the decomposition. Zero corresponds to no
             stretching present. Relatively insensitive and typically adjusted in powers of 10.
         eta : float
-            The sparsity factor than influences the decomposition. Should be set to zero for
+            The sparsity factor that influences the decomposition. Should be set to zero for
             non-sparse data such as PDF. Can be used to improve results for sparse data such
             as XRD, but due to instability, should be used only after first selecting the
-            best value for rho.
+            best value for rho. Suggested adjustment is by powers of 2.
         max_iter : int
             The maximum number of times to update each of A, X, and Y before stopping
             the optimization.