Add changelog entry for 1.0.0-beta.7 (#398)

Author: Slavek Kabrda

CHANGELOG.md

@@ -1,5 +1,15 @@
 # CHANGELOG
 
+## v1.0.0-beta.7 / 2020-07-22
+
+* [Added] Adding four usage attribution endpoints. See [#393](https://github.com/DataDog/datadog-api-client-go/pull/393).
+* [Added] Fix documentation for `v1/hosts`. See [#383](https://github.com/DataDog/datadog-api-client-go/pull/383).
+* [Changed] Update synthetics test to contain latest features. See [#375](https://github.com/DataDog/datadog-api-client-go/pull/375).
+* [Added] Usage Billable Summary response. See [#368](https://github.com/DataDog/datadog-api-client-go/pull/368).
+* [Added] Add Logs Search API v2. See [#365](https://github.com/DataDog/datadog-api-client-go/pull/365).
+* [Fixed] RRULE property for Downtimes API. See [#364](https://github.com/DataDog/datadog-api-client-go/pull/364).
+* [Deprecated] Dashboards List v1 has been deprecated. See [#363](https://github.com/DataDog/datadog-api-client-go/pull/363).
+
 ## v1.0.0-beta.6 / 2020-06-19
 
 * [Fixed] Update enum of synthetics devices IDs to match API. See [#351](https://github.com/DataDog/datadog-api-client-go/pull/351).