Attempt to resolve forward test in docs

Author: Tyler Slabinski

doc/borrow_mut.md

@@ -13,9 +13,9 @@ When `BorrowMut` is derived for a newtype or struct with one field, a single
 implementation is generated to expose the underlying field.
 
 ```rust
+# #[macro_use] extern crate derive_more;
 # use core::borrow::Borrow;
 # use core::borrow::BorrowMut;
-# #[macro_use] extern crate derive_more;
 # fn main(){}
 #[derive(Borrow, BorrowMut)]
 struct MyWrapper(String);
@@ -24,9 +24,9 @@ struct MyWrapper(String);
 Generates:
 
 ```rust
+# #[macro_use] extern crate derive_more;
 # use core::borrow::Borrow;
 # use core::borrow::BorrowMut;
-# #[macro_use] extern crate derive_more;
 # #[derive(Borrow)]
 # struct MyWrapper(String);
 impl BorrowMut<String> for MyWrapper {
@@ -41,8 +41,9 @@ to the `borrow_mut` implementation of the field. So here `SigleFieldForward`
 implements all `BorrowMut` for all types that `Vec<i32>` implements `BorrowMut` for.
 
 ```rust
-# use core::borrow::BorrowMut;
 # #[macro_use] extern crate derive_more;
+# use core::borrow::Borrow;
+# use core::borrow::BorrowMut;
 #[derive(Borrow, BorrowMut)]
 #[borrow(forward)]
 #[borrow_mut(forward)]
@@ -61,6 +62,13 @@ This generates:
 # #[macro_use] extern crate derive_more;
 # #[derive(Borrow)]
 # struct SingleFieldForward(Vec<i32>);
+# impl <__BorrowT: ?::core::marker::Sized> ::core::borrow::Borrow<__BorrowT> for
+# SingleFieldForward where Vec<i32>: ::core::borrow::Borrow<__BorrowT> {
+#    #[inline]
+#    fn borrow(&self) -> &__BorrowT {
+#        <Vec<i32> as ::core::borrow::Borrow<__BorrowT>>::borrow(&self.0)
+#    }
+# }
 impl<__BorrowMutT: ?::core::marker::Sized> ::core::borrow::BorrowMut<__BorrowMutT> for SingleFieldForward
 where
     Vec<i32>: ::core::borrow::BorrowMut<__BorrowMutT>,
@@ -81,9 +89,9 @@ An implementation will be generated for each indicated field.
 You can also exclude a specific field by using `#[borrow_mut(ignore)]`.
 
 ```rust
+# #[macro_use] extern crate derive_more;
 # use core::borrow::Borrow;
 # use core::borrow::BorrowMut;
-# #[macro_use] extern crate derive_more;
 # fn main(){}
 #[derive(Borrow, BorrowMut)]
 struct MyWrapper {
@@ -102,9 +110,9 @@ struct MyWrapper {
 Generates:
 
 ```
+# #[macro_use] extern crate derive_more;
 # use core::borrow::Borrow;
 # use core::borrow::BorrowMut;
-# #[macro_use] extern crate derive_more;
 # #[derive(Borrow)]
 # struct MyWrapper {
 #     name: String,
@@ -128,9 +136,9 @@ Note that `BorrowMut<T>` may only be implemented once for any given type `T`. Th
 mark more than one field of the same type with `#[borrow_mut]` will result in a compilation error.
 
 ```compile_fail
+# #[macro_use] extern crate derive_more;
 # use core::borrow::Borrow;
 # use core::borrow::BorrowMut;
-# #[macro_use] extern crate derive_more;
 # fn main(){}
 // Error! Conflicting implementations of BorrowMut<String>
 #[derive(BorrowMut)]