Update postgrest-on-docker installation/tutorial documentation

[mweenem]

As a Postgrest newbie, I recently managed to install and run Postgrest-on-docker-on-win10 but after much difficulty and great support from @laurenceisla because the guidance is misleading and incorrect in some cases - this is the original that I raised. The main reason is that it focuses on native installs, and there are gaps in the docker installation guidance - this applies to Tutorial 0, Tutorial 1, and Installation sections. I suggest a clear split in the guidance for the two processes as there are many differences. I found that the following process which I used, provides a clear, clean Postgres installation on docker/win10. i also found that installing pgadmin4 container to view db content is also a really useful feature - guidance is available here.

-------- STEP 1 --------------------------- #load and run docker images with following docker-compose.yml content which starts postgres + postgrest + swagger servers and creates "postgres" as db owner with full rights. > docker-compose up

version: '3'
services:
  server:
    image: postgrest/postgrest
    ports:
      - "3000:3000"
    environment:
      PGRST_DB_ANON_ROLE: postgres
      PGRST_DB_URI: postgres://postgres:mysecretpassword@db:5432/postgres
      PGRST_OPENAPI_SERVER_PROXY_URI: http://127.0.0.1:3000
      PGRST_DB_SCHEMAS: api
    depends_on:
      - db
  db:
    image: postgres
    ports:
      - "5432:5432"
    environment:
      POSTGRES_DB: postgres
      POSTGRES_USER: postgres
      POSTGRES_PASSWORD: mysecretpassword
  swagger:
    image: swaggerapi/swagger-ui
    ports:
      - "8080:8080"
    expose:
      - "8080"
    environment:
      API_URL: http://localhost:3000/
  # Uncomment this if you want to persist the data.
  #  volumes:
  #   - "C:\<your-volume-directory>:/var/lib/postgresql/data"

-------- STEP 2 ----------------------------- #start psql shell for with "postgres" as user - this will produce "postgres=#" cursor > docker exec -it postgrest-db-1 psql -U postgres

-------- STEP 3 -----------------------------

execute following psql commands to create postgres db roles and tables for API

postgres=# create schema api;
create table api.todos (
  id serial primary key,
  done boolean not null default false,
  task text not null,
  due timestamptz
);
insert into api.todos (task) values
  ('finish tutorial 0'), ('pat self on back');
create role web_anon nologin;
grant usage on schema api to web_anon;
grant select on api.todos to web_anon;
create role authenticator noinherit login password 'mysecretpassword';
grant web_anon to authenticator;

-------- STEP 4 -----------------------------

execute curl command to invoke postgrest API which returns todos table content below

> curl http://localhost:3000/todos

StatusCode        : 200
StatusDescription : OK
Content           : [{"id":1,"done":false,"task":"finish tutorial 0","due":null},
                     {"id":2,"done":false,"task":"pat self on back","due":null}]
RawContent        : HTTP/1.1 200 OK
                    Transfer-Encoding: chunked
                    Content-Range: 0-1/*
                    Content-Location: /todos
                    Content-Type: application/json; charset=utf-8
                    Date: Wed, 12 Oct 2022 19:28:11 GMT
                    Server: postgrest/10.0....
Forms             : {}
Headers           : {[Transfer-Encoding, chunked], [Content-Range, 0-1/*], [Content-Location, /todos], [Content-Type, application/json; charset=utf-8]...}
Images            : {}
InputFields       : {}
Links             : {}
ParsedHtml        : mshtml.HTMLDocumentClass
RawContentLength  : 123