Update v0.3.0 guide

guides/upgrading/v0.3.0.md

@@ -2,22 +2,31 @@
 
 ## Add `Beacon.Plug` to your Router
 
-In your application's `router.ex`, first find the pipeline used for your beacon_site.  It is usually `:browser` but you can check:
+In your application's `router.ex` file, first find where your sites are defined:
 
 ```elixir
-scope "/" do
+scope "/", MyAppWeb do
   pipe_through :browser
   beacon_site "/", site: :my_site
 end
 ```
 
-In the above case we can see the pipeline is `:browser`.  Still in the router, look for that pipeline and add `plug Beacon.Plug`:
+In the above case we can see the site `:my_site` is inside a scope piped through `:browser`,
+so let's add a new `:beacon` pipeline with the `Beacon.Plug`:
 
 ```elixir
-pipeline :browser do
-  ...
+pipeline :beacon do
   plug Beacon.Plug
 end
 ```
 
-Now the `Beacon.Plug` will ensure consistent rendering, particularly important when Page Variants are used.
+And add that pipeline into the existing scope:
+
+```elixir
+scope "/", MyAppWeb do
+  pipe_through [:browser, :beacon] # <- add the pipeline here
+  beacon_site "/", site: :my_site
+end
+```
+
+Now the `Beacon.Plug` will ensure consistent rendering, particularly important when Page Variants are used.