By Alicia Powell and Rollo Ross (Reuters) – As hip-hop prepares to turn 50 in 2023, U.S. rapper Nas wants to make sure the world understands its history, relevance and influence. Through his company, Mass Appeal, the native New Yorker is spearheading numerous events leading up to the anniversary. On Aug. 11, 1973, Clive Campbell, also known as DJ Kool Herc, played at a New York City block party and was credited with starting the music genre. Tributes will include a series of documentary films produced in conjunction with TV network Showtime, as well as 10 EP soundtracks produced by Swizz Beatz…