replace ../ with ../../std/ to support core docs

Author: matthew-piziak

src/libcore/ops.rs

@@ -217,7 +217,7 @@ macro_rules! forward_ref_binop {
 /// [std::time::SystemTime] implements `Add<Duration>`, which permits
 /// operations of the form `SystemTime = SystemTime + Duration`.
 ///
-/// [std::time::SystemTime]: ../time/struct.SystemTime.html
+/// [std::time::SystemTime]: ../../std/time/struct.SystemTime.html
 #[lang = "add"]
 #[stable(feature = "rust1", since = "1.0.0")]
 pub trait Add<RHS=Self> {
@@ -290,7 +290,7 @@ add_impl! { usize u8 u16 u32 u64 isize i8 i16 i32 i64 f32 f64 }
 /// [std::time::SystemTime] implements `Sub<Duration>`, which permits
 /// operations of the form `SystemTime = SystemTime - Duration`.
 ///
-/// [std::time::SystemTime]: ../time/struct.SystemTime.html
+/// [std::time::SystemTime]: ../../std/time/struct.SystemTime.html
 #[lang = "sub"]
 #[stable(feature = "rust1", since = "1.0.0")]
 pub trait Sub<RHS=Self> {