Add release notes for 5.2.1

release-notes/5.2.1.md

+# CiviCRM 5.2.1
+
+Released June 8, 2018
+
+- **[Synopsis](#synopsis)**
+- **[Bugs resolved](#bugs)**
+- **[Credits](#credits)**
+- **[Feedback](#feedback)**
+
+## <a name="synopsis"></a>Synopsis
+
+| *Does this version...?*                                         |         |
+|:--------------------------------------------------------------- |:-------:|
+| Fix security vulnerabilities?                                   |   no    |
+| Change the database schema?                                     |   no    |
+| Alter the API?                                                  |   no    |
+| Require attention to configuration options?                     |   no    |
+| Fix problems installing or upgrading to a previous version?     |   no    |
+| Introduce features?                                             |   no    |
+| **Fix bugs?**                                                   | **yes** |
+
+## <a name="bugs"></a>Bugs resolved
+
+- **Fix regression in 5.2.0 when contribution reports include soft-credit column
+  ([12286](https://github.com/civicrm/civicrm-core/pull/12286))**
+
+## <a name="credits"></a>Credits
+
+This release was developed by the following authors and reviewers:
+
+JMA Consulting - Monish Deb; Lighthouse Design and Consulting - Brian
+Shaughnessy; Wikimedia Foundation - Eileen McNaughton
+
+## <a name="feedback"></a>Feedback
+
+These release notes are edited by Tim Otten and Andrew Hunt.  If you'd like to
+provide feedback on them, please login to https://chat.civicrm.org/civicrm and
+contact `@agh1`.