fix: added error to examplePairingObject

fixes #363

spec.md

@@ -237,6 +237,7 @@ Field Name | Type | Description
 <a name="example-pairing-summary"></a>summary | `string` | Short description for the example pairing.
 <a name="example-pairing-params"></a>params | [[Example Object](#example-object) \| [Reference Object](#reference-object)] | **REQUIRED** Example parameters.
 <a name="example-pairing-result"></a>result | [Example Object](#example-object) \| [Reference Object](#reference-object) | Example result. When not provided, the example pairing represents usage of the method as a notification.
+<a name="example-pairing-error"></a>error | [Example Object](#example-object) \| [Reference Object](#reference-object) | Represents an example error response. The provided [Example Object](#example-object) MUST have the entire error object as its value. If provided, the [`examplePairing.result`](#example-pairing-result) must not be provided.
 
 This object MAY be extended with [Specification Extensions](#specification-extensions).