Fix missing id properties in docs example (#6395)

This example contains a list of person objects, but only the first 3 have id properties. This appears to be a mistake; in the next use of the list all 5 person objects have this property, but it is not changed as part of an instructive exercise.

This change makes the final two with objects consistent with the remainder of the list.

Author: jpayoung

src/content/learn/rendering-lists.md

@@ -113,9 +113,11 @@ const people = [{
   name: 'Mohammad Abdus Salam',
   profession: 'physicist',
 }, {
+  id: 3,
   name: 'Percy Lavon Julian',
   profession: 'chemist',  
 }, {
+  id: 4,
   name: 'Subrahmanyan Chandrasekhar',
   profession: 'astrophysicist',
 }];