Topkg_mainEntry point for pkg.ml files.
val describe : 
  ?delegate:Topkg_cmd.t ->
  ?readmes:Topkg_pkg.std_file list ->
  ?licenses:Topkg_pkg.std_file list ->
  ?change_logs:Topkg_pkg.std_file list ->
  ?metas:Topkg_pkg.meta_file list ->
  ?opams:Topkg_pkg.opam_file list ->
  ?lint_files:Topkg_fpath.t list option ->
  ?lint_custom:(unit -> Topkg_result.R.msg Topkg_result.result list) ->
  ?distrib:Topkg_distrib.t ->
  ?publish:Topkg_publish.t ->
  ?build:Topkg_build.t ->
  string ->
  (Topkg_conf.t -> Topkg_install.t list Topkg_result.result) ->
  unit