Update asyncapi.md

spec/asyncapi.md

@@ -569,7 +569,7 @@ Describes the operations available on a single channel.
 
 Field Name | Type | Description
 ---|:---:|---
-<a name="channelItemObjectRef"></a>$ref | `string` | Allows for an external definition of this channel item. The referenced structure MUST be in the format of a [Channel Item Object](#channelItemObject). If there are conflicts between the referenced definition and this Channel Item's definition, the behavior is *undefined*. <br/><br/>**Deprecated:** Using $ref with sibling fixed fields has been deprecated. Usage without any siblings is still encouraged!
+<a name="channelItemObjectRef"></a>$ref | `string` | Allows for an external definition of this channel item. The referenced structure MUST be in the format of a [Channel Item Object](#channelItemObject). If there are conflicts between the referenced definition and this Channel Item's definition, the behavior is *undefined*. <br/><br/>**Deprecated:** Using the $ref field has been deprecated when accompanied by other fields.
 <a name="channelItemObjectDescription"></a>description | `string` | An optional description of this channel item. [CommonMark syntax](https://spec.commonmark.org/) can be used for rich text representation.
 <a name="channelItemObjectServers"></a>servers | [`string`] | The servers on which this channel is available, specified as an optional unordered list of names (string keys) of [Server Objects](#serverObject) defined in the [Servers Object](#serversObject) (a map). If `servers` is absent or empty then this channel must be available on all servers defined in the [Servers Object](#serversObject).
 <a name="channelItemObjectSubscribe"></a>subscribe | [Operation Object](#operationObject) | A definition of the SUBSCRIBE operation, which defines the messages produced by the application and sent to the channel.