update changelog

Author: siirimangus

CHANGELOG.md

@@ -7,6 +7,8 @@ The file format of it is based on [Keep a Changelog](http://keepachangelog.com/e
 For public Changelog covering all changes done to Pipedrive’s API, webhooks and app extensions platforms, see [public Changelog](https://pipedrive.readme.io/docs/changelog) with discussion area in [Developers Community](https://devcommunity.pipedrive.com/c/documentation/changelog/19).
 
 ## [Unreleased]
+
+## 17.5.2
 ### Changed
 - Updated endpoint descriptions to warn about permanently removing deleted entities:
   - `DELETE /activities`
@@ -20,6 +22,7 @@ For public Changelog covering all changes done to Pipedrive’s API, webhooks an
   - `DELETE /persons/{id}`
   - `DELETE /products/{id}`
 - Updated `conditions` parameter description for `POST /filters` and `PUT /filters/{id}`
+
 ## 17.5.1
 ### Fixed
 - Fixed custom field value (it should return null if the value is null)