Add release notes for 20226

Author: Ben Hillis

WSL/release-notes.md

@@ -10,6 +10,11 @@ ms.localizationpriority: high
 
 # Release Notes for Windows Subsystem for Linux
 
+## Build 20226
+For general Windows information on build 20226 visit the [Windows blog](https://blogs.windows.com/windows-insider/2020/09/10/announcing-windows-10-insider-preview-build-20226/).
+
+* Fix crash in LxssManager service. [GH 5902]
+
 ## Build 20211
 For general Windows information on build 20211 visit the [Windows blog](https://blogs.windows.com/windows-insider/2020/09/10/announcing-windows-10-insider-preview-build-20211/).