Fix syntax highlighting

Doc-FAQ-Cheatsheet.md

@@ -112,14 +112,14 @@ for value in values.iter() {  // value: &int
 
 [Phantom types](http://www.haskell.org/haskellwiki/Phantom_type) are types that cannot be constructed at compile time. To express these in rust, zero-variant `enum`s can be used:
 
-~~~rust
+```rust
 enum Open {}
 enum Closed {}
-~~~
+```
 
 Phantom types are useful for enforcing state at compile time. For example:
 
-~~~rust
+```rust
 struct Door<State>(~str);
 
 fn close(Door(name): Door<Open>) -> Door<Closed> {
@@ -130,9 +130,9 @@ fn open(Door(name): Door<Closed>) -> Door<Open> {
     Door(name)
 }
 
-close(Door::<Open>(~"front"))      // ok
-close(Door::<Closed>(~"front"))    // error: mismatched types: expected `main::Door<main::Open>` but found `main::Door<main::Closed>`
-~~~
+close(Door::<Open>(~"front"));      // ok
+close(Door::<Closed>(~"front"));    // error: mismatched types: expected `main::Door<main::Open>` but found `main::Door<main::Closed>`
+```
 
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