Nixify CircleCI setup (#1535)

* package ghr
* add nix-based release scripts
* refactor CI based on nix tests and release scripts
* update stack version in circleci
* update makefile
* remove docker directory
* add Docker Hub description
* add README on docker

nix/docker/postgrest.conf

@@ -1,7 +1,15 @@
+# See https://postgrest.org/en/stable/configuration.html#configuration
+
+# Required settings
+
 db-uri = "$(PGRST_DB_URI)"
 db-schema = "$(PGRST_DB_SCHEMA)"
 db-anon-role = "$(PGRST_DB_ANON_ROLE)"
+
+# Optional settings
+
 db-pool = "$(PGRST_DB_POOL)"
+db-pool-timeout = "$(PGRST_DB_POOL_TIMEOUT)"
 db-extra-search-path = "$(PGRST_DB_EXTRA_SEARCH_PATH)"
 
 server-host = "$(PGRST_SERVER_HOST)"