Adding notes on the SPFx extension support

Author: VesaJuvonen

docs/apis/communication-site-creation-rest.md

@@ -2,9 +2,6 @@
 
 Learn how to create and get the status of a new modern SharePoint Communication site with the REST interface.
 
-> [!NOTE]
-> There is a known bug with this API which is blocking completely this behavior. Fix will be rolling gradually to SharePoint Online by end of October 2017.
-
 ## Prerequisites
 
 This topic assumes that you are already familiar with the topics Get to know the SharePoint REST service and Complete basic operations using SharePoint REST endpoints. It does not provide code snippets.

docs/spfx/extensions/overview-extensions.md

@@ -12,6 +12,9 @@ SharePoint Framework Extensions enable you to extend the SharePoint user experie
 
 You can build extensions alongside common scripting frameworks, such as AngularJS and React, in addition to plain JavaScript projects. For example, you can use React along with components from Office UI Fabric React to create experiences based on the same components used in Office 365.
 
+> [!NOTE]
+> There is a known bug with list and library extension support in the classic experiences. These only work currently in context of modern team sites aka. group associated team sites. Work is being done to address this issue. 
+
 ## Get started
 If you haven't installed the SharePoint Framework, follow the steps to [Set up your development environment](../set-up-your-development-environment.md).