fix up the readme and sample .env to smooth out first dev experience (#976)

* chore: fix up the readme and sample .env to smooth out first dev experience

* fix indentation

.env.sample

@@ -3,18 +3,20 @@
 # keys (for auth) and the SECRET_KEY.
 #
 # Please use `openssl rand -hex 32` to create SECRET_KEY
-
-DATABASE_URL=postgres://user:pass@localhost:5432/outline
-DATABASE_URL_TEST=postgres://user:pass@localhost:5432/outline-test
 SECRET_KEY=generate_a_new_key
-PORT=3000
-REDIS_URL=redis://localhost:6379
+
+DATABASE_URL=postgres://user:pass@postgres:5432/outline
+DATABASE_URL_TEST=postgres://user:pass@postgres:5432/outline-test
+REDIS_URL=redis://redis:6379
+
 URL=http://localhost:3000
+PORT=3000
+
 DEPLOYMENT=self
 ENABLE_UPDATES=true
 SUBDOMAINS_ENABLED=false
 WEBSOCKETS_ENABLED=true
-DEBUG=sql,cache,presenters,events
+DEBUG=cache,presenters,events
 
 # Third party signin credentials (at least one is required)
 SLACK_KEY=get_a_key_from_slack

README.md

@@ -31,8 +31,12 @@ In development you can quickly get an environment running using Docker by follow
 
 1. Install [Docker for Desktop](https://www.docker.com) if you don't already have it.
 1. Register a Slack app at https://api.slack.com/apps
-1. Copy the file `.env.sample` to `.env` and fill out the Slack keys, everything
-   else should work well for development.
+1. Copy the file `.env.sample` to `.env`
+1. Fill out the following fields:
+    1. `SECRET_KEY` (follow instructions in the comments of `.env`)
+    1. `SLACK_KEY` (this is called "Client ID" in Slack admin)
+    1. `SLACK_SECRET`
+1. Add `http://localhost:3000/auth/slack.callback` as an Oauth callback URL in Slack Admin
 1. Run `make up`. This will download dependencies, build and launch a development version of Outline.
 
 For production deployment by building from scratch, you can follow these steps: