Merge pull request #978 from keob/fix-typo

Update char-bool.md

src/basic/base-type/char-bool.md

@@ -8,7 +8,7 @@
 
 下面的代码展示了几个颇具异域风情的字符：
 
-```
+```rust
 fn main() {
     let c = 'z';
     let z = 'ℤ';