Update pennylane/devices/_qubit_device.py

Co-authored-by: lillian542 <38584660+lillian542@users.noreply.github.com>

pennylane/devices/_qubit_device.py

@@ -1065,12 +1065,16 @@ def vn_entropy(self, wires, log_base):
 
     def vn_entanglement_entropy(self, wires0, wires1, log_base):
         r"""Returns the Von Neumann entanglement entropy prior to measurement.
+        
         .. math::
+        
             S(\rho_A) = -\text{Tr}[\rho_A \log \rho_A] = -\text{Tr}[\rho_B \log \rho_B] = S(\rho_B)
+            
         Args:
             wires0 (Sequence[int] or int): the wires of the first subsystem
             wires1 (Sequence[int] or int): the wires of the second subsystem
             log_base (float): Base for the logarithm.
+            
         Returns:
             float: returns the Von Neumann entropy
         """