Update week2.do.txt

Author: mhjensen

doc/src/week2/week2.do.txt

@@ -13,7 +13,7 @@ o introduced the inner product and showed how to calculate it in an orthonormal
 o introduced outer products and projection operators
 o introduced tensor products and showed how to construct state vectors for multiple qubits
 !eblock
-Most of the material can be found in Scherer, Mathematics of Quantum Computations, chapter 2
+Most of the material can be found in Scherer, Mathematics of Quantum Computations, chapter 2, available electronically via UiO's subscription.
 
 
 !split