Try to fix hyperlinks in the README (again)

tatsuya6502 · tatsuya6502 · commit 9425ce17423a · 2019-06-22T15:38:40.000+08:00
diff --git a/README.md b/README.md
@@ -22,9 +22,9 @@
 
 If you want a template with English source code comments, please request it to us by filing [a GitHub issue][gh-issue].
 
-[ja-branch]: /tree/ja
-[vendor-ja-branch]: /tree/vendor-ja
-[gh-issue]: /issues
+[ja-branch]: https://github.com/rust-lang-ja/atcoder-rust-base/tree/ja
+[vendor-ja-branch]: https://github.com/rust-lang-ja/atcoder-rust-base/tree/vendor-ja
+[gh-issue]: https://github.com/rust-lang-ja/atcoder-rust-base/issues
 
 
 ## ライセンス / License
