adding external package separator

Author: davidchesnut

misc/SharePointReferenceToc.xml

@@ -176,6 +176,8 @@
 				<Item text="IWebPartPropertiesMetadata" url="spfx/sp-webpart-base/interface/iwebpartpropertiesmetadata" SEODescription=""/>
 			</Item>
 		</Item>
+		<Item text="horizontalline" url="/" IsSeparation="true" />
+        <Item text="External packages" url="spfx/web-apis-module" SEODescription="" />
 		<Item text="web-apis" url="spfx/web-apis-module" SEODescription="">
 			<Item text="Classes" url="spfx/web-apis" SEODescription="">
 				<Item text="Body" url="spfx/web-apis/class/body" SEODescription=""/>