Update docs: readFromParcel() is not necessary to make a class support

<li>Make your class implement the {@link android.os.Parcelable} interface.</li>

<li>Implement the method <code>public void writeToParcel(Parcel out)</code> that takes the

current state of the object and writes it to a parcel.</li>

<li>Implement the method <code>public void readFromParcel(Parcel in)</code> that reads the

value in a parcel into your object.</li>

<li>Add a static field called <code>CREATOR</code> to your class which is an object implementing

the {@link android.os.Parcelable.Creator Parcelable.Creator} interface.</li>