Merge "docs: Updating Android TV recommendations docs" into mnc-docs

<ul>

<li><strong>Continuation content</strong> recommendations for the next episode for users to resume

watching a series.</li>

watching a series. Or, use continuation recommendations for paused movies, TV shows, or podcasts

so users can get back to watching paused content in just a few clicks.</li>

<li><strong>New content</strong> recommendations, such as for a new first-run episode, if the user

finished watching another series.

<li><strong>Related content</strong> recommendations based on the users historic viewing behavior.

finished watching another series. Also, if your app lets users subscribe to, follow, or track

content, use new content recommendations for unwatched items in their list of tracked content.</li>

<li><strong>Related content</strong> recommendations based on the users' historic viewing behavior.

</li>

</ul>

<p>For more information on how to design recommendation cards for the best user experience, see

<a href="https://www.google.com/design/spec-tv/system-overview/recommendation-row.html#recommendation-row-card-customization"

class="external-link">Recommendation Row</a> in the Android TV Design Spec.</p>

<h3 id="grouping">Grouping Recommendations</h3>

<p>

You can optionally group recommendations based on recommendation source. For example, your app

might provide two groups of recommendations: recommendations for content the user is subscribed to,

and recommendations for new trending content the user might not be aware of.

</p>

<p>

The system ranks and orders recommendations for each group separately when creating or updating

the recommendation row. By providing group information for your recommendations, you can ensure

that your recommendations don’t get ordered below unrelated recommendations.

</p>

<p>

Use

{@link android.support.v4.app.NotificationCompat.Builder#setGroup

NotificationCompat.Builder.setGroup()} to set the group key string of a recommendation. For

example, to mark a recommendation as belonging to a group that contains new trending content,

you might call <code>setGroup("trending")</code>.

</p>

<h2 id="service">Create a Recommendations Service</h2>