added external packages node

Author: davidchesnut

misc/SharePointReferenceToc.xml

@@ -1,7 +1,6 @@
 <?xml version="1.0" encoding="utf-8"?>
 <Menu xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:xsd="http://www.w3.org/2001/XMLSchema" SupportedProduct="|SharePoint" SupportedVersion="|V1.0|">
 	<Item text="SharePoint Framework Reference" url="spfx" SEODescription="Reference documentation for the SharePoint Framework">
-		<Item text="Internal modules" url="spfx/internal-modules" SEODescription=""/>
 		<Item text="sp-webpart-base" url="spfx/sp-webpart-base" SEODescription="">
 			<Item text="Classes" url="spfx/sp-webpart-base/class" SEODescription="">
 				<Item text="BaseClientSideWebPart" url="spfx/sp-webpart-base/class/baseclientsidewebpart" SEODescription=""/>
@@ -135,7 +134,7 @@
 			</Item>
 		</Item>
 		<Item text="horizontalline" url="/" IsSeparation="true" />
-		<Item text="External modules" url="spfx/external-modules" SEODescription=""/>
+		<Item text="External packages" url="spfx/external-packages" SEODescription=""/>
 		<Item text="es6-collections" url="spfx/es6-collections-module" SEODescription="">
 			<Item text="Interfaces" url="spfx/es6-collections" SEODescription="">
 				<Item text="ForEachable" url="spfx/es6-collections.api/interface/foreachable" SEODescription=""/>

reference/spfx/external-packages.md

@@ -0,0 +1,9 @@
+# External packages
+
+External packages are typings provided for 3rd party packages used by the SharePoint Framework.
+
+| External package   | Description                                             |
+|--------------------|---------------------------------------------------------|
+| [es6-collections](es6-collections.md) |                     |
+| [es6-promise](es6-promise.md)         |                     |
+| [whatwg-fetch](whatwg-fetch.md)       |                     |