Add example for AEP-214

aep/general/0214/aep.md.j2

@@ -47,7 +47,31 @@ message ExpiringResource {
 }
 ```
 
-{% tab oas %} **Note:** OAS content not yet written.
+{% tab oas %}
+
+```yaml
+schema:
+  type: object
+  properties:
+    expire_time:
+      type: string
+      format: date-time
+      description: >
+        Timestamp in UTC of when this resource is considered expired. This is
+        *always* provided on output, regardless of what was sent on input.
+    ttl:
+      type: string
+      format: duration
+      description: The TTL for this resource.
+      x-aep-field:
+        behavior:
+          - INPUT_ONLY
+  oneOf:
+    - required:
+        - expire_time
+    - required:
+        - ttl
+```
 
 {% endtabs %}