add acknowledgement

Author: simonbyrne

README.md

@@ -6,6 +6,10 @@ Implements Singular Value Decomposition for generic number types, such as `BigFl
 
 It uses a Golub-Kahan 2-stage algorithm of bidiagonalization with Householder reflections, followed by an implicit QR with shift.
 
+## Acknowledgements
+
+Based on initial code by Andreas Noack.
+
 ## References
 
 * Golub, G. H. and Van Loan, C. F. (1996), "§8.6.2 The SVD Algorithm", *Matrix Computations* (3rd Ed.), Johns Hopkins University Press, Baltimore, MD, USA.