Update week4.do.txt

Author: mhjensen

doc/src/week4/week4.do.txt

@@ -8,7 +8,7 @@ DATE: February 11, 2026
 o Reminder from last week on Entanglement, entropy and density matrices
 o One-qubit and two-qubit gates, background and realizations
 o Simple Hamiltonian systems and start discussion of project 1
-o Introduction to qiskit a
+o Introduction to qiskit (for exercise sessions).
 #o "Video of lecture":"https://youtu.be/UcfOVvFyw2E"
 #o "Whiteboard notes":"https://github.com/CompPhysics/QuantumComputingMachineLearning/blob/gh-pages/doc/HandWrittenNotes/2025/NotesFebruary12.pdf"