Merge pull request #1427 from r00ster91/patch-1

Fix code highlighting in some places

Author: marioidival

src/expression.md

@@ -2,7 +2,7 @@
 
 A Rust program is (mostly) made up of a series of statements:
 
-```
+```rust,editable
 fn main() {
     // statement
     // statement
@@ -13,7 +13,7 @@ fn main() {
 There are a few kinds of statements in Rust. The most common two are declaring
 a variable binding, and using a `;` with an expression:
 
-```
+```rust,editable
 fn main() {
     // variable binding
     let x = 5;

src/hello/print/print_display.md

@@ -108,7 +108,7 @@ each requires its own implementation. This is detailed further in
 ### Activity
 
 After checking the output of the above example, use the `Point2D` struct as a
-guide to add a Complex struct to the example. When printed in the same
+guide to add a `Complex` struct to the example. When printed in the same
 way, the output should be:
 
 ```txt

src/primitives/tuples.md

@@ -64,7 +64,7 @@ fn main() {
 
 ### Activity
 
- 1. *Recap*: Add the `fmt::Display` trait to the Matrix `struct` in the above example,
+ 1. *Recap*: Add the `fmt::Display` trait to the `Matrix` struct in the above example,
     so that if you switch from printing the debug format `{:?}` to the display
     format `{}`, you see the following output: