Update repo url and add license section to readme

Author: bjorn3

Cargo.toml

@@ -6,7 +6,7 @@ license = "Apache-2.0 WITH LLVM-exception"
 description = "A writer for object file ar archives"
 keywords = ["ar", "archive"]
 readme = "Readme.md"
-repository = "https://github.com/bjorn3/ar_archive_writer"
+repository = "https://github.com/rust-lang/ar_archive_writer"
 
 # See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
 

Readme.md

@@ -1,3 +1,14 @@
 # A writer for object file ar archives
 
 This is based on commit [8ef3e895a](https://github.com/llvm/llvm-project/tree/8ef3e895ad8ab1724e2b87cabad1dacdc7a397a3) of LLVM's archive writer.
+
+## License
+
+Licensed under Apache License v2.0 with LLVM Exceptions
+([LICENSE.txt](LICENSE.txt) or https://llvm.org/LICENSE.txt)
+
+### Contribution
+
+Unless you explicitly state otherwise, any contribution intentionally submitted
+for inclusion in the work by you shall be dual licensed as above, without any
+additional terms or conditions.