What is the dual benefit of a devotee writing and sharing a detailed Guru biography, as explained in the text?

The text outlines a powerful dual benefit that arises from a devotee undertaking the task of writing a detailed poetic Guru biography. As stated in Chapter 0, the writer first performs a form of Guru service through the very act of creating the biography. Secondly, when other devotees study this work and perform Parayans, the writer gains the merit of serving God in humanity (Jan-Janardan) and performing public service. This process also helps those other devotees in their spiritual journey to achieve the purpose of their lives.