Santa wish list for Dgraph in 2021

[wildan2711 (Wildan Maulana Syahidillah)]

• [DQL] Sort indexes, or anything to improve the below issue:
  Offset-based pagination is slow - #6 by diggy
  Usecase: user feeds with infinite scroll
• [DQL] Random nodes function
  Pick random node - #9 by EnricoMi
  Usecase: friend recommendations
• [DQL] tf-idf scoring on term search
  Feature request: full text search with tf-idf Scoring - #8 by diggy
• [DQL] Unique indexes
• [DQL] Composite indexes
• [DQL] Geo Distance function
  Add @distance for geo