Relabel license to upstream policy (label-accuracy fix per LICENSE_AUDIT.md)

README.md

@@ -1,5 +1,7 @@
 ---
-license: cc-by-4.0
+license: other
+license_name: iau-mpc-policy
+license_link: https://www.minorplanetcenter.net/iau/WWWPolicy.html
 pretty_name: "MPC Comet Orbital Elements"
 language:
   - en
@@ -128,4 +130,5 @@ Source code: [juliensimon/space-datasets](https://github.com/juliensimon/space-d
 
 ## License
 
-[CC-BY-4.0](https://creativecommons.org/licenses/by/4.0/)
+
+[IAU Minor Planet Center Policy](https://www.minorplanetcenter.net/iau/WWWPolicy.html)