What constitutes a 'Guru's biography' as described in the text, and what are the dual benefits of creating and studying one?

Chapter 0 defines a Guru's biography as a reliable and true book that describes the Guru's incarnation, from childhood to old age, including their wonderful plays (Leelas), incomparable miracles, and the works of their incarnation. The benefits are twofold. Firstly, the writer of a detailed poetic Guru biography performs Guru service through their effort. Secondly, when other devotees study and perform Parayans of that work, the writer gains the additional merit of serving God in humanity (Jan-Janardan), while those devotees are also able to achieve the purpose of their own lives.