According to the preface, what are the mutual benefits for the author and the community when a Guru's biography is written and studied?

Chapter 0 details a symbiotic relationship between the author of a Guru biography and the community of devotees. The author performs Guru service by undertaking the study and composition of the detailed work. When other devotees then study and perform Parayans of this biography, the author gains the additional merit of serving 'God in humanity' (Jan-Janardan) and engaging in public service. For the community, this collective study and devotion helps them achieve the purpose of their lives. This process fosters a strong community built on shared service and spiritual growth.