Fix references tin text o check-expression

Should refer to checking-expr

lang/spec.html

@@ -6760,9 +6760,9 @@ <h3>Checking expression</h3>
 Evaluates expression resulting in value v. If v has basic type error, then
 </p>
 <ul>
-<li>if the checking-keyword is <code>check</code>, then the check-expression
+<li>if the checking-keyword is <code>check</code>, then the checking-expr
 completes abruptly with a check-fail with associated value v;</li>
-<li>if the checking-keyword is <code>checkpanic</code>, then the check-expression
+<li>if the checking-keyword is <code>checkpanic</code>, then the checking-expr
 completes abruptly with a panic with associated value v.</li>
 </ul>
 <p>