update CHANGELOG (#31)

CHANGELOG.md

@@ -15,23 +15,52 @@ Types of changes:
 ## [Unreleased]
 
 ### Added
+- Sphinx docs and examples added for pyqasm ([#20](https://github.com/qBraid/pyqasm/pull/20))
+- qBraid header check enabled in format action([#29](https://github.com/qBraid/pyqasm/pull/29))
+- Integrated code coverage with codecov ([#30](https://github.com/qBraid/pyqasm/pull/30))
 
 ### Improved / Modified
 - Housekeeping updates involving codeowners, workflows, pyproject, and readme ([#16](https://github.com/qBraid/pyqasm/pull/16))
+- Fixed parsing of compile-time constants for register sizes. Statements like `const int[32] N = 3; qubit[N] q;` are now supported ([#21](https://github.com/qBraid/pyqasm/pull/21)).
+- Update project `README.md` ([#22](https://github.com/qBraid/pyqasm/pull/22))
 - Updated sphinx docs page ([#26](https://github.com/qBraid/pyqasm/pull/26))
+- **Major Change**: The default type for `pyqasm.unroller.unroll` has been changed from `pyqasm.elements.Qasm3Module` to `str`. This change is backward-incompatible and will require users to update their code. The following code snippet demonstrates the change - 
+
+```python
+from pyqasm.unroller import unroll
+qasm_str = """
+OPENQASM 3;
+qubit[3] q;
+h q;
+"""
+
+# Old way : The default type for unroll was pyqasm.elements.Qasm3Module
+program = unroll(qasm_str, as_module=True)
+unrolled_qasm_old = program.unrolled_qasm
+
+# New way : The default type for unroll is now str
+unrolled_qasm_new = unroll(qasm_str)
+```
+To force the return type to be `pyqasm.elements.Qasm3Module`, users can set the `as_module` parameter to `True` as shown above to update their code.
 
 ### Deprecated
 
 ### Removed
 
 ### Fixed
+- Issue with aliasing of qubits was fixed where aliased qubits were referenced with non-aliased qubits in a quantum gate ([#14](https://github.com/qBraid/pyqasm/pull/14)). The following program is now supported - 
 
-### Dependencies
+```python
+OPENQASM 3;
+include "stdgates.inc";
+qubit[4] q;
+let alias = q[0:2];
+cx alias[1], q[2];
+```
 
-## [0.0.0] - 2024-10-04
+- Issue with subroutines, when `return` keyword was absent, was fixed in ([#21](https://github.com/qBraid/pyqasm/pull/21))
 
-### Added
-- Setup basic project/repo template ([#1](https://github.com/qBraid/pyqasm/pull/1))
-- Configured PyPI workflows ([#2](https://github.com/qBraid/pyqasm/pull/2))
-- Add initial implementation ([#3](https://github.com/qBraid/pyqasm/pull/3))
-- Added test workflows and contribution templates ([#6](https://github.com/qBraid/pyqasm/pull/6))
+### Dependencies
+
+## References
+[Changelog for release v0.0.1](https://github.com/qBraid/pyqasm/releases/tag/v0.0.1)