Update get case activity

Author: cnasikas

docs/cases/api/cases-api/cases-api-get-case-activity.asciidoc

@@ -106,6 +106,23 @@ A JSON array containing all user activity for the specified case.
     "action_id": "223f7bd0-750a-11ea-b83a-553aecdb28b6",
     "case_id": "293f1bc0-74f6-11ea-b83a-553aecdb28b6",
     "comment_id": "21a844e0-750a-11ea-b83a-553aecdb28b6"
-  }
+  },
+  {
+      "action_field":[
+         "connector"
+      ],
+      "action":"update",
+      "action_at":"2020-10-12T16:03:34.940Z",
+      "action_by":{
+         "email":"christos.nasikas@elastic.co",
+         "full_name":"Christos Nasikas",
+         "username":"cnasikas"
+      },
+      "new_value":"{\"id\":\"18bc18cf-bd5d-4c88-bcdd-c7bb52a692cd\",\"name\":\"Resilient\",\"type\":\".resilient\",\"fields\":{\"incidentTypes\":[\"1001\"],\"severityCode\":\"5\"}}",
+      "old_value":"{\"id\":\"72b9fa3a-b081-487d-9358-61d5da2968c1\",\"name\":\"Jira\",\"type\":\".jira\",\"fields\":{\"issueType\":\"10006\",\"parent\":null,\"priority\":\"Medium\"}}",
+      "action_id":"7c326760-0ca4-11eb-8a58-a3c589db8483",
+      "case_id":"7498ae50-0c8c-11eb-aefc-797bf7d42db4",
+      "comment_id":null
+   }
 ]
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