chored: updated the link in README.rst

Author: Tingwen Zhang

README.rst

@@ -132,7 +132,7 @@ trying to commit again.
 
 Improvements and fixes are always appreciated.
 
-Before contribuing, please read our `Code of Conduct <https://github.com/diffpy/diffpy.structure/blob/main/CODE_OF_CONDUCT.rst>`_.
+Before contribuing, please read our `Code of Conduct <https://github.com/diffpy/diffpy.structure/blob/main/CODE-OF-CONDUCT.rst>`_.
 
 Acknowledgement
 ---------------