Add HttpPutFormContentFilter note to documentation

Update reference guide to include a note about the use of
HttpPutFormContentFilter in combination with @RequestBody
MultiValueMap and HttpEntity.

Issue: SPR-8415

src/reference/docbook/mvc.xml

@@ -2157,6 +2157,14 @@ public class EditPetForm {
         available through the
         <literal>ServletRequest.getParameter*()</literal> family of
         methods.</para>
+
+        <note>
+          <para>As <classname>HttpPutFormContentFilter</classname> consumes the body of the
+          request, it should not be configured for PUT or PATCH URLs that rely on other
+          converters for <literal>application/x-www-form-urlencoded</literal>. This includes
+          <literal>@RequestBody MultiValueMap&lt;String, String&gt;</literal> and
+          <literal>HttpEntity&lt;MultiValueMap&lt;String, String&gt;&gt;</literal>.</para>
+        </note>
       </section>
 
       <section xml:id="mvc-ann-cookievalue">