fix(docs): clarify defaultFn

Signed-off-by: Muhammad Aaqil <aaqilcs102@gmail.com>

Author: aaqilniz

docs/site/Model.md

@@ -523,7 +523,18 @@ Here are general attributes for property definitions:
           <li><code>"uuidv4"</code>: generate a new universally unique identifier using the UUID version 4 algorithm.</li>
           <li>"<code>now"</code>: use the current date and time as returned by <code>new Date()</code></li>
         </ul>
-        NOTE: the value of <code>defaultFn</code> is generated by LoopBack itself. If you'd like to use database built-in <code>uuid</code> functions (MySQL or Postgres for example), please check the README file of the corresponding connector.
+        NOTES:
+        <ul>
+          <li>
+            the value of <code>defaultFn</code> is generated by LoopBack itself. If you'd like to use database built-in <code>uuid</code> functions (MySQL or Postgres for example), please check the README file of the corresponding connector.
+          </li>
+          <li>
+            don't set <code>generated</code> to <code>true</code> incase of <code>defaultFn</code> as <code>generated</code> property indicates the value to be generated by the database not by Loopback.
+          </li>
+          <li>
+            don't set <code>required</code> to <code>true</code> incase of <code>defaultFn</code> as <code>required</code> means the user needs to provide the field in the request always.
+          </li>
+        </ul>
       </td>
     </tr>
     <tr>