Chap03 -> Creating function-based component -> Children props, added explanation

QandA/frontend/src/HomePage.tsx

@@ -8,7 +8,8 @@ export const HomePage = () => (
   <Page>
     <div>
       <PageTitle>Unanswered Questions</PageTitle>
-      <button>Ask a question</button>
+      <button>Ask a question</button>{' '}
+      {/* This button component is passed as children of Page */}
     </div>
     <QuestionList data={getUnansweredQuestions()} />
   </Page>