fixed highlighting

patterns/compose-structs.md

@@ -41,7 +41,7 @@ fn main(a: &mut A) {
 We can apply this design pattern and refactor `A` into two smaller structs, thus
 solving the borrow checking issue:
 
-```
+```rust
 // A is now composed of two structs - B and C.
 struct A {
     b: B,

patterns/newtype.md

@@ -7,7 +7,7 @@ This creates a new type, rather than an alias to a type (`type` items).
 
 ## Example
 
-```
+```rust
 // Some type, not necessarily in the same module or even crate.
 struct Foo {
     ...
@@ -80,7 +80,7 @@ most common uses, but they can be used for other reasons:
 * making a type with copy semantics have move semantics,
 * abstraction by providing a more concrete type and thus hiding internal types, e.g.,
 
-```
+```rust
 pub struct Foo(Bar<T1, T2>);
 ```