Merge: * openapi changelog

Squashed commit of the following:

commit 7f254a4abf0cbb0f9f7bfea754632115cacc0918
Author: Simon Zolin <s.zolin@adguard.com>
Date:   Fri Mar 13 12:08:09 2020 +0300

    * openapi changelog

openapi/CHANGELOG.md

@@ -6,6 +6,7 @@
 ### API: Refresh filters: POST /control/filtering/refresh
 
 * Added "whitelist" boolean parameter
+* Response is in JSON format
 
 Request:
 
@@ -15,6 +16,14 @@ Request:
 		"whitelist": true
 	}
 
+Response:
+
+	200 OK
+
+	{
+		"updated": 123 // number of filters updated
+	}
+
 
 ## v0.100: API changes