docs(architecture/glossary): describe modules,barrels, and bundles; refer to doc

closes #547

public/docs/ts/latest/guide/architecture.jade

@@ -77,14 +77,18 @@ figure
 :marked
   Some modules are libraries of other modules.
   
-  Angular itself ships as a collection of library modules. 
+  Angular itself ships as a collection of library modules called "barrels". 
-  Each Angular library is actually a facade over several feature modules that belong together as a group.
+  Each Angular library is actually a public facade over several logically related private modules.
   
   The `angular2/core` library is the primary Angular library module from which we get most of what we need.
   <br clear="all">
   
   There are other important Angular library modules too such as `angular2/common`, `angular2/router`, and `angular2/http`.
-
+.l-sub-section
+  :marked
+     Learn more about how Angular organizes and distributes modules 
+     in "[Modules, barrels and bundles](https://github.com/angular/angular/blob/master/modules/angular2/docs/bundles/overview.md)".  
+:marked
   We import what we need from an Angular library module in much the same way. 
   For example, we import the Angular **`Component` *function*** from the *angular2/core* module like this:
 +makeExample('architecture/ts/app/app.component.ts', 'import')(format=".")

public/docs/ts/latest/guide/glossary.jade

@@ -33,6 +33,23 @@
 
 .l-main-section
 <a id="B"></a>
+:marked
+  ## Barrel
+.l-sub-section
+  :marked
+    A **barrel** is an Angular library module consisting of a logical grouping of single-purpose modules
+    such as `Component` and `Directive`.
+    
+    Familiar barrels include `angular2/core`, `angular2/common`, `angular2/platform/browser`,
+    `angular2/http`, and `angular2/router`.
+   
+    Barrels are packaged and shipped as [**bundles**](#bundle) that 
+    we may load with script tags in our `index.html`.
+   
+    The script, `angular2.dev.js`, is a bundle.
+   
+    Learn more in "[Modules, barrels and bundles](https://github.com/angular/angular/blob/master/modules/angular2/docs/bundles/overview.md)".
+
 :marked
   ## Binding
 .l-sub-section
@@ -55,6 +72,23 @@
 
     One can bootstrap multiple apps in the same `index.html`, each with its own top level root.
 
+:marked
+  ## Bundle
+.l-sub-section
+  :marked
+    Angular JavaScript libraries are shipped in **bundles** within an **npm package**
+    such as [angular2](https://www.npmjs.com/package/angular2). 
+    
+    The scripts `angular2.dev.js`, `http.js`, `router.js`, and `Rx.js` are
+    familiar examples of bundles.
+    
+    A bundle contains one more more [**barrels**](#barrel)
+    and each barrel contains a collection of logically related [modules](#module)
+  
+    Familiar barrels include `angular2/core`, `angular2/common`, `angular2/platform/browser`,
+    `angular2/http`, `angular2/router`.
+
+    Learn more in "[Modules, barrels and bundles](https://github.com/angular/angular/blob/master/modules/angular2/docs/bundles/overview.md)".
 
 .l-main-section
 <a id="C"></a>
@@ -342,6 +376,29 @@
 
 .l-main-section
 <a id="M"></a>
+:marked
+  ## Module
+.l-sub-section
+  :marked
+    Angular apps are modular.
+
+    In general we assemble our application from many modules both the ones we write ourselves
+    and the ones we acquire from others.
+
+    A typical module is a cohesive block of code dedicated to a single purpose.
+    
+    A module exports something of value in that code, typically one thing such as a class.
+    Modules are typically named after the file in which the exported thing is defined.
+    
+    The Angular [DatePipe](https://github.com/angular/angular/blob/master/modules/angular2/src/common/pipes/date_pipe.ts)
+    class belongs to a module named `date_pipe` in the file `date_pipe.ts`.
+    
+    In general, Angular feature modules such as the `data_pipe` are not exposed directly. 
+    Rather they are grouped together with logically related modules in public-facing **library modules**
+    called [**barrels**](#barrel).
+    
+    Learn more in "[Modules, barrels and bundles](https://github.com/angular/angular/blob/master/modules/angular2/docs/bundles/overview.md)".
+
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