Fix japanese rust by example url

ja_JP.md

@@ -5,6 +5,6 @@
 * [**プログラミング言語Rust**](http://rust-lang-ja.github.io/the-rust-programming-language-ja/1.6/book/)
 * 公式ドキュメント [The Rust Programming Language](https://doc.rust-lang.org/book/) の和訳
 * Japanese translation of the official book: The Rust Programming Language
-* [**Rust by Example**](http://rust-lang-ja.org/rust-by-example/)
+* [**Rust by Example**](https://doc.rust-jp.rs/rust-by-example-ja/)
 * [Rust by Example](https://doc.rust-lang.org/stable/rust-by-example/) の和訳
 * Japanese translation of Rust by Example