[nix] remove devops/corenlp dir, update README, add 'nil' to nix pkgs

4 jobs for issue-436-dockerfile-and-corenlp in 44 minutes and 10 seconds (queued for 5 seconds)
Status Job ID Name Coverage
  Cabal
passed #17518
cabal

00:17:29

 
  Stack
passed #17519
stack

00:03:14

 
  Bench
manual #17520
allowed to fail manual
bench
 
  Test
passed #17521
test

00:23:26