Add links to definitions of terminology ...

... in the definition for what an expression that
“has an extended temporary scope” is.

Improvement discussed in and motivated by the question in this [thread on URLO].

[thread on URLO]: https://users.rust-lang.org/t/how-to-understand-extending-based-on-expressions/87068/16?u=steffahn

Author: steffahn

src/destructors.md

@@ -271,8 +271,9 @@ let x = &mut 0;
 println!("{}", x);
 ```
 
-If a borrow, dereference, field, or tuple indexing expression has an extended
-temporary scope then so does its operand. If an indexing expression has an
+If a [borrow][borrow expression], [dereference][dereference expression],
+[field][field expression], or [tuple indexing expression] has an extended
+temporary scope then so does its operand. If an [indexing expression] has an
 extended temporary scope then the indexed expression also has an extended
 temporary scope.
 
@@ -384,8 +385,12 @@ variable or field from being dropped automatically.
 [block expression]: expressions/block-expr.md
 [borrow expression]: expressions/operator-expr.md#borrow-operators
 [cast expression]: expressions/operator-expr.md#type-cast-expressions
+[dereference expression]: expressions/operator-expr.md#the-dereference-operator
+[field expression]: expressions/field-expr.md
+[indexing expression]: expressions/array-expr.md#array-and-slice-indexing-expressions
 [struct expression]: expressions/struct-expr.md
 [tuple expression]: expressions/tuple-expr.md#tuple-expressions
+[tuple indexing expression]: expressions/tuple-expr.md#tuple-indexing-expressions
 
 [`for`]: expressions/loop-expr.md#iterator-loops
 [`if let`]: expressions/if-expr.md#if-let-expressions