Update text in overview fragment

mailbox-android/src/main/res/layout/fragment_overview.xml

@@ -12,9 +12,12 @@
 		android:layout_width="wrap_content"
 		android:layout_height="wrap_content"
 		android:layout_margin="8dp"
-		android:text="Your mailbox is not paired with a Briar account.
+		android:gravity="center"
+		android:padding="@dimen/margin_large"
+		android:text="Your mailbox is not paired with a Briar account.\n
 		Press + to pair with Briar."
 		android:textColor="@color/briar_text_primary"
+		android:textSize="@dimen/text_size_large"
 		app:layout_constraintEnd_toEndOf="parent"
 		app:layout_constraintStart_toStartOf="parent"
 		app:layout_constraintTop_toTopOf="parent"/>