A prominent author and historian will offer his thoughts on the Rev. Martin Luther King Jr., and a vocalist who has performed with the Boston Pops will perform a musical version of King’s historic “I Have a Dream” speech in a livestream concert at the end of this month. Milton Community Concerts will feature a group of Black performers and composers, plus reflections by National Book Award winner Ibram X. Kendi in the benefit “Still Dreaming: A Musical Tribute” taking place on Sunday, Jan. 31, at 3 p.m.