Update documentation to reflect the old approach not working.

activity like this can cause it to be mixed with your normal application back stack

in undesired ways.  To make it behave correctly, in the manifest declaration

for the activity the attributes 

<code>android:launchMode="singleInstance"</code> and

<code>android:launchMode="singleTask"</code>,

<code>android:taskAffinity=""</code> and

<code>android:excludeFromRecents="true"</code>

must be set.  The full activity declaration for this sample is:</p>

{@sample development/samples/ApiDemos/AndroidManifest.xml interstitial_affinity}

<p>Because of the use of <code>singleInstance</code>, you must be careful about launching

any other activities from this one.  These activities will be launched

in their own task, and care must be taken to make sure this interacts

well with the current state of your application's task.  This is essentially

<p>You must be careful when launching other activities from this initial activity,

because this is not a top-level part of the application, does not appear in

recents, and needs to be relaunched at any point from the notification with new data

to show.  This best approach is to make sure any activity launched from it is

launched in its own task.  When doing this care must be taken to make sure this

new task interacts well with the current state of your exiting application's

task.  This is essentially

the same as switching to the main application as described for the Email style

notification shown before.  Given the <code>makeMessageIntentStack()</code>

method previously shown, handling a click here would look something like this:</p>

method previously shown, handling a click then would look something like this:</p>

{@sample development/samples/ApiDemos/src/com/example/android/apis/app/IncomingMessageInterstitial.java

  app_launch}

<p>If you don't want to use the <code>singleInstance</code> launch mode for

this activity, an alternative approach is to use <code>android:taskAffinity=""</code>.

This tells Android that the activity should not be treated as part of the

main application flow, so it will not get mixed together with that.  All of the

other issues discussed here do still apply, though this would allow you to start

additional activities that are part of this notification task instead of switching

to and replacing the main application task.</p>

<h2 id="ManageYourNotifications">Managing your Notifications</h2>

<p>The {@link android.app.NotificationManager} is a system service that manages all