destructors.md: improve readability by adding pauses

Had to read second sentence twice to more easily understand it, something the pause would have helped avoid.
diff --git a/src/destructors.md b/src/destructors.md
index 1e03a31..5713c3c 100644
--- a/src/destructors.md
+++ b/src/destructors.md
@@ -401,7 +401,7 @@
 ```
 
 r[destructors.scope.lifetime-extension.sub-expressions]
-If a [borrow], [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.
+If a [borrow], [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.
 
 r[destructors.scope.lifetime-extension.patterns]
 #### Extending based on patterns