Docs: Add header strings in bit.rs and register.rs

crates/circuit/src/bit.rs

@@ -1,3 +1,15 @@
+// This code is part of Qiskit.
+//
+// (C) Copyright IBM 2025
+//
+// This code is licensed under the Apache License, Version 2.0. You may
+// obtain a copy of this license in the LICENSE.txt file in the root directory
+// of this source tree or at http://www.apache.org/licenses/LICENSE-2.0.
+//
+// Any modifications or derivative works of this code must retain this
+// copyright notice, and modified files need to carry a notice indicating
+// that they have been altered from the originals.
+
 use std::fmt::Debug;
 
 /// Keeps information about where a bit is located within the circuit.

crates/circuit/src/register.rs

@@ -1,3 +1,15 @@
+// This code is part of Qiskit.
+//
+// (C) Copyright IBM 2025
+//
+// This code is licensed under the Apache License, Version 2.0. You may
+// obtain a copy of this license in the LICENSE.txt file in the root directory
+// of this source tree or at http://www.apache.org/licenses/LICENSE-2.0.
+//
+// Any modifications or derivative works of this code must retain this
+// copyright notice, and modified files need to carry a notice indicating
+// that they have been altered from the originals.
+
 use indexmap::IndexSet;
 use pyo3::{exceptions::PyTypeError, intern, types::PyAnyMethods, FromPyObject};
 use std::{