Pull request: * home, openapi: improve docs and responses

Merge in DNS/adguard-home from 2243-better-docs to master

Closes #2243.

Squashed commit of the following:

commit 26c655a0e4339528870633c2cdf39c3b5c486b1d
Author: Ainar Garipov <A.Garipov@AdGuard.COM>
Date:   Thu Nov 5 12:51:43 2020 +0300

    * openapi: improve more

commit dc0ab9857787d14eb0686814a4f3c8f917698bee
Author: Ainar Garipov <A.Garipov@AdGuard.COM>
Date:   Tue Nov 3 20:40:32 2020 +0300

    * home, openapi: improve docs and responses

openapi/openapi.yaml

@@ -1137,9 +1137,18 @@ components:
             type: object
             description: Filtering URL settings
             properties:
+                data:
+                    properties:
+                        enabled:
+                            type: boolean
+                        name:
+                            type: string
+                        url:
+                            type: string
+                    type: object
                 url:
                     type: string
-                enabled:
+                whitelist:
                     type: boolean
         FilterRefreshRequest:
             type: object
@@ -1466,6 +1475,8 @@ components:
                     description: URL or an absolute path to the file containing filtering rules
                     type: string
                     example: https://filters.adtidy.org/windows/filters/15.txt
+                whitelist:
+                    type: boolean
         RemoveUrlRequest:
             type: object
             description: /remove_url request data