Clarify that ProblemDetails can be extended for any reason.

index.html

@@ -4792,8 +4792,7 @@ <h3>Problem Details</h3>
           </dd>
           <dt>code</dt>
           <dd>
-The `code` <a>property</a> is an OPTIONAL
-<a data-cite="RFC9457#name-extension-members">RFC9457 extension member</a>. If
+The `code` <a>property</a> is an OPTIONAL value. If
 present, its value MUST be an integer that identifies the type of the problem.
 Integer codes are useful in systems that only provide integer return values.
           </dd>
@@ -4809,12 +4808,6 @@ <h3>Problem Details</h3>
           </dd>
         </dl>
 
-        <p>
-Other properties that are useful for debugging purposes MAY be included in
-a <a>ProblemDetails</a> object. See [[RFC9457]] for further guidance on
-using this mechanism.
-        </p>
-
         <p>
 The following problem description types and codes are defined by this
 specification:
@@ -4851,6 +4844,13 @@ <h3>Problem Details</h3>
           </dd>
         </dl>
 
+        <p>
+Implementations MAY extend the <a>ProblemDetails</a> object by specifying
+additional types, codes, or properties. See the
+<a data-cite="RFC9457#name-extension-members">Extension Member</a> section
+in [[RFC9457]] for further guidance on using this mechanism.
+        </p>
+
       </section>
 
     </section>