Update qiskit_ibm_runtime/options/twirling_options.py

Co-authored-by: Rebecca Dimock <[email protected]>

qiskit_ibm_runtime/options/twirling_options.py

@@ -97,7 +97,7 @@ class TwirlingOptions:
 
     .. image:: /source_images/twirling_strategy_options.png
       :alt: Image illustrating the differences among twirling strategies. If "active", only
-            instruction qubits in each layer will be twirled. If "active-circuit" the union of 
+            instruction qubits in each layer will be twirled. If "active-circuit", 
             all instruction qubits in the circuit will be twirled. If "active-accum", the union 
             of instructions qubits in the circuit up to the current twirled layer will be twirled. 
             Finally, if "all", all qubits in the input circuit will be twirled in each twirled layer.