Update changelog for 5.26.0

CHANGELOG.md

@@ -3,6 +3,20 @@ Datadog Agent 6 has been officially released and the release notes can be found
 Changes
 =======
 
+# 5.26.0 / 08-01-2018
+
+**Linux, Windows, Docker and Source Install**
+
+### Details
+https://github.com/DataDog/dd-agent/compare/5.25.3...5.26.0
+
+### Changes
+Please refer to the [Integrations Core Checks 5.26.0 tag](https://github.com/DataDog/integrations-core/releases/tag/5.25.3) for the list of changes on the core checks.
+
+Please refer to the [Trace Agent 6.4.1 tag](https://github.com/DataDog/datadog-trace-agent/releases/tag/6.3.3) for more information on the Trace Agent.
+
+Please refer to the [Process Agent 5.26.0 tag](https://github.com/DataDog/datadog-process-agent/releases/tag/5.25.3) for more information on the Process Agent.
+
 # 5.25.3 / 07-17-2018 
 
 **Linux, Windows, Docker and Source Install**