How can devotees serve their Guru and build a community through literature, according to the preface?

The preface explains that a Sadguru accepts service from devotees through books in two primary ways. One way is by having their biographies written by devotees. When a writer creates a detailed poetic biography, they perform a Guru service. This service extends to the community when other devotees study this work and perform Parayans (devotional readings). As stated in Chapter 0, this allows the writer to gain merit by serving God in humanity, and the other devotees also achieve the purpose of their lives, thus fostering a shared spiritual practice.