Fix null being converted to empty object in the examples (#468)

Author: m-murasovs

content/docs/api_v2/api_v2_reference.apib

@@ -3758,7 +3758,7 @@ a summary of your limits, and your current usage.
 - username:              `janedoe`                         (string, nullable)
 - createdAt:             `2018-10-26T07:23:14.855Z`         (string, required)
 - modifiedAt:            `2018-10-26T13:30:49.578Z`         (string, required)
-- removedAt:             `null`                             (string, nullable)
+- removedAt                                                 (string, nullable)
 - stats                                                     (object, nullable)
     - totalRuns:         15                                 (number, required)
 - options                                                   (object, nullable)
@@ -3812,7 +3812,7 @@ a summary of your limits, and your current usage.
 - username:              `janedoe`                          (string, nullable)
 - createdAt:             `2018-10-26T07:23:14.855Z`         (string, required)
 - modifiedAt:            `2018-10-26T13:30:49.578Z`         (string, required)
-- removedAt:             `null`                             (string, nullable)
+- removedAt                                                 (string, nullable)
 - stats                                                     (object, nullable)
     - totalRuns:         15                                 (number, required)
 - options                                                   (object, nullable)
@@ -4177,7 +4177,7 @@ a summary of your limits, and your current usage.
 - actId:            `janedoe~my-actor`         (string, required)
 - userId:           `PNWZBd7Z9c746JAnF`        (string, required)
 - startedAt:        `2019-11-30T07:34:24.202Z` (string, required)
-- finishedAt:       null (string, required)
+- finishedAt                                   (string, nullable)
 - status:           `RUNNING`                  (string, required)
 - meta                                         (object, required)
     - origin:       `WEB`                      (string, required)