Merge "docs: Clarified when you can put the fragments in the root view." into mnc-preview-docs

<p>To get started, your layout must include a {@link android.view.ViewGroup} in which you place

each {@link android.app.Fragment} associated with a tab. Be sure the {@link android.view.ViewGroup}

has a resource ID so you can reference it from your code and swap the tabs within it.

Alternatively, if the tab content will fill the activity layout, then your activity doesn't need a

layout at all (you don't even need to call {@link android.app.Activity#setContentView

setContentView()}). Instead, you can place each fragment in the default root view, which you can

refer to with the {@code android.R.id.content} ID.</p>

</p>

<p>Once you determine where the fragments appear in the layout, the basic procedure to add tabs

is:</p>