Fix phase in readme state (#11259) (#11263)

(cherry picked from commit fced4bf)

Co-authored-by: Jake Lishman <jake.lishman@ibm.com>

README.md

@@ -51,7 +51,7 @@ qc_example.cx(0,1)       # 0th-qubit-Controlled-NOT gate on 1st qubit
 qc_example.cx(0,2)       # 0th-qubit-Controlled-NOT gate on 2nd qubit
 ```
 
-This simple example makes an entangled state known as a [GHZ state](https://en.wikipedia.org/wiki/Greenberger%E2%80%93Horne%E2%80%93Zeilinger_state) $(|000\rangle + |111\rangle)/\sqrt{2}$. It uses the standard quantum gates: Hadamard gate (`h`), Phase gate (`p`), and CNOT gate (`cx`). 
+This simple example makes an entangled state known as a [GHZ state](https://en.wikipedia.org/wiki/Greenberger%E2%80%93Horne%E2%80%93Zeilinger_state) $(|000\rangle + i|111\rangle)/\sqrt{2}$. It uses the standard quantum gates: Hadamard gate (`h`), Phase gate (`p`), and CNOT gate (`cx`). 
 
 Once you've made your first quantum circuit, choose which primitive function you will use. Starting with `sampler`,
 we use `measure_all(inplace=False)` to get a copy of the circuit in which all the qubits are measured: