Remove unnecessary raw stirngs.

src/fn_args.rs

@@ -40,11 +40,12 @@ pub trait FuncArgs {
     /// let engine = Engine::new();
     /// let mut scope = Scope::new();
     ///
-    /// let ast = engine.compile(r#"
-    ///         fn hello(x, y, z) {
-    ///             if x { `hello ${y}` } else { y + z }
-    ///         }
-    /// "#)?;
+    /// let ast = engine.compile(
+    /// "
+    ///     fn hello(x, y, z) {
+    ///         if x { `hello ${y}` } else { y + z }
+    ///     }
+    /// ")?;
     ///
     /// let result: String = engine.call_fn(&mut scope, &ast, "hello", options)?;
     ///