fix title in proptypes and string required

Author: DusanSacha

exercises/proptypes/problem.en.md

@@ -62,7 +62,7 @@ class TodoList extends React.Component {
                   <tbody>
                     <Todo title="Shopping">Milk</Todo>
                     <Todo title="Hair cut">13:00</Todo>
-                    <Todo>15:00</Todo>
+                    <Todo title="Learn React">15:00</Todo>
                   </tbody>
                 </table>
             </div>
@@ -81,7 +81,7 @@ class Todo extends React.Component {
     }
 }
 Todo.propTypes = {
-    title: PropTypes.number.isRequired
+    title: PropTypes.string.isRequired
 };
 
 class TodoForm extends React.Component {

exercises/proptypes/problem.ko.md

@@ -61,7 +61,7 @@ class TodoList extends React.Component {
                   <tbody>
                     <Todo title="Shopping">Milk</Todo>
                     <Todo title="Hair cut">13:00</Todo>
-                    <Todo>15:00</Todo>
+                    <Todo title="Learn React">15:00</Todo>
                   </tbody>
                 </table>
             </div>
@@ -80,7 +80,7 @@ class Todo extends React.Component {
     }
 }
 Todo.propTypes = {
-    title: PropTypes.number.isRequired
+    title: PropTypes.string.isRequired
 };
 
 class TodoForm extends React.Component {

exercises/proptypes/problem.md

@@ -58,7 +58,7 @@ class TodoList extends React.Component {
                   <tbody>
                     <Todo title="Shopping">Milk</Todo>
                     <Todo title="Hair cut">13:00</Todo>
-                    <Todo>15:00</Todo>
+                    <Todo title="Learn React">15:00</Todo>
                   </tbody>
                 </table>
             </div>
@@ -77,7 +77,7 @@ class Todo extends React.Component {
     }
 }
 Todo.propTypes = {
-    title: PropTypes.number.isRequired
+    title: PropTypes.string.isRequired
 };
 
 class TodoForm extends React.Component {