Fix book-example tests

book-example/src/format/mathjax.md

@@ -16,6 +16,6 @@ To indicate a block equation
 
 use
 
-```
+```bash
 \\[ \mu = \frac{1}{N} \sum_{i=0} x_i \\]
 ```

book-example/src/format/rust.md

@@ -5,23 +5,23 @@
 There is a feature in mdBook that let's you hide code lines by prepending them with a `#`.
 
 ```bash
-#fn main() {
+# fn main() {
     let x = 5;
     let y = 6;
 
     println!("{}", x + y);
-#}
+# }
 ```
 
 Will render as
 
 ```rust
-#fn main() {
+# fn main() {
     let x = 5;
     let y = 7;
 
     println!("{}", x + y);
-#}
+# }
 ```
 
 

book-example/src/format/theme/syntax-highlighting.md

@@ -28,23 +28,23 @@ There is a feature in mdBook that let's you hide code lines by prepending them w
 
 
 ```bash
-#fn main() {
+# fn main() {
     let x = 5;
     let y = 6;
 
     println!("{}", x + y);
-#}
+# }
 ```
 
 Will render as
 
 ```rust
-#fn main() {
+# fn main() {
     let x = 5;
     let y = 7;
 
     println!("{}", x + y);
-#}
+# }
 ```
 
 **At the moment, this only works for code examples that are annotated with `rust`. Because it would collide with semantics of some programming languages. In the future, we want to make this configurable through the `book.json` so that everyone can benefit from it.**