make LICENSE as CC0

README.md

@@ -56,5 +56,4 @@ You can also see all versions in [The Release](https://github.com/atcoder/ac-lib
 
 ## License
 
-- The header files in `atcoder` folder are licensed under a [CC0](https://creativecommons.org/publicdomain/zero/1.0/legalcode) license.
-- TODO: We haven't determined the license of other files.
+This library is released under the [CC0](https://creativecommons.org/publicdomain/zero/1.0/legalcode), except for the third-party libraries that are located under `/document_(en|ja)/lib` directory. Please refer [/document_en/lib/LICENSE.md](./document_en/lib/LICENSE.md) for details.

document_en/index.md

@@ -55,4 +55,4 @@
 
 ## License
 
-The header files in `atcoder` folder are licensed under a CC0 license. See `atcoder/LICENSE` for further details.
+The files are licensed under a CC0 license, except for the third-party libraries located in the `/document_en/lib`, `/document_ja/lib` directory.

document_ja/index.md

@@ -54,4 +54,5 @@
 
 ## ライセンス
 
-ヘッダファイル群(同梱の `atcoder` フォルダ以下)はCC0ライセンスで公開しています。詳しくは`atcoder/LICENSE`を参照してください。
+`/document_en/lib`, `/document_ja/lib` 以下で再配布しているライブラリを除きCC0ライセンスで公開しています。
+

tools/generate_zip.py

@@ -28,3 +28,4 @@
             zipf.write(f, f.relative_to(Path('..')))
 
         zipf.write('../expander.py', 'expander.py')
+        zipf.write('../LICENSE', 'LICENSE')