Add documentation on REPL Driven Development

[oxalorg]

How to use this project with the REPL can immensely help beginners/new contributors.

For example testing queries directly with the REPL can be done like this:

;; in the repl.clj file
(comment
  (require '[clojurians-log.db.queries :as queries])
  (d/q '[:find ?msg
         :where
         [?chan :channel/name "clojure"]
         [?msg :message/channel ?chan]]
     (db))
 )

Ensure the repl.clj file is loaded in the REPL and then evaluate everything inside the comment form.