(docs): fix license url (#37909)

Summary:
Update the license url on the documentation because it throws 404 page not found

## Changelog:

[General] [Fixed] - License on the documentation throws 404 page not found

Pull Request resolved: #37909

Test Plan: Click the LICENSE and should open the license page

Reviewed By: GijsWeterings

Differential Revision: D46760941

Pulled By: hoxyq

fbshipit-source-id: f2522c51606ed5776aa6ae325143887749cc4d3a

README.md

@@ -143,5 +143,5 @@ React Native is MIT licensed, as found in the [LICENSE][l] file.
 
 React Native documentation is Creative Commons licensed, as found in the [LICENSE-docs][ld] file.
 
-[l]: https://github.com/facebook/react-native/blob/HEAD/LICENSE
+[l]: https://github.com/facebook/react-native/blob/main/packages/react-native/LICENSE
 [ld]: https://github.com/facebook/react-native/blob/HEAD/LICENSE-docs