removed release notes folder for webhooks release.

Author: chakkaradeep

misc/SharePointDocumentationToc.xml

@@ -25,10 +25,6 @@
 				<Item text="Known issues" url="spfx/web-parts/basics/known-issues" SEODescription="Known issues with web parts in the SharePoint Framework" />
 			</Item>
 		</Item>
-		<Item text="Release notes" url="spfx/release-notes" SEODescription="">
-			<Item text="Developer Preview Drop 2" url="spfx/release-notes/sharepoint-framework-dev-preview-drop2" SEODescription="" />
-			<Item text="Developer Preview Drop 1" url="spfx/release-notes/sharepoint-framework-dev-preview-drop1" SEODescription="" />
-		</Item>
 	</Item>
 	<Item text="SharePoint APIs" url="apis" SEODescription="">
 		<Item text="Webhooks" url="apis/webhooks" SEODescription="">