Docs: Apply suggestions from code review

- Correct incorrect docstrings for `qubits()` and `clbits()`

Co-authored-by: Eli Arbel <[email protected]>

crates/circuit/src/circuit_data.rs

@@ -1166,12 +1166,12 @@ impl CircuitData {
         &self.global_phase
     }
 
-    /// Returns an immutable view of the Qubit register of the circuit
+    /// Returns an immutable view of the Qubits registered in the circuit
     pub fn qubits(&self) -> &BitData<Qubit> {
         &self.qubits
     }
 
-    /// Returns an immutable view of the Classical register of the circuit
+    /// Returns an immutable view of the Classical bits registered in the circuit
     pub fn clbits(&self) -> &BitData<Clbit> {
         &self.clbits
     }