Update docs for RelativeLayout to better explain its interpretation of

     * Describes how the child views are positioned. Defaults to

     * <code>Gravity.LEFT | Gravity.TOP</code>.

     *

     * <p>Note that since RelativeLayout considers the positioning of each child

     * relative to one another to be significant, setting gravity will affect

     * the positioning of all children as a single unit within the parent.

     * This happens after children have been relatively positioned.</p>

     *

     * @param gravity See {@link android.view.Gravity}

     *

     * @see #setHorizontalGravity(int)