Resolve "Group Note doesn't show"

Closes #58 (closed)

src/main/resources/templates/group/teacher_view.html

@@ -33,7 +33,7 @@
             <div class="boxed-group">
                 <h1 class="section-title" th:text="|#{edition.instructor_note}: ${group.name}|"></h1>
                 <form class="form" th:object="${note}" th:action="@{|/group/note?page=group|}" method="post">
-                    <input type="hidden" th:name="entityId.id" th:value="${group.id}"/>
+                    <input type="hidden" th:name="entityId.groupId" th:value="${group.id}"/>
                     <div class="form-column">
                                 <textarea th:name="note" th:text="${group.note?.note}" class="textarea"
                                           th:placeholder="#{edition.instructor_note}" rows=6