Remove double slash

Author: Havvy

src/expressions/field-expr.md

@@ -31,7 +31,7 @@ separate entities when borrowing. If the struct does not implement
 [`Drop`](../special-types-and-traits.md#drop) and is stored in a local variable,
 this also applies to moving out of each of its fields. This also does not apply
 if automatic dereferencing is done though user defined types other than
-[`Box`](..//special-types-and-traits.html#boxt).
+[`Box`](../special-types-and-traits.html#boxt).
 
 ```rust
 struct A { f1: String, f2: String, f3: String }