Add back a cleaner and leaner .env.production.sample (#14206)

.env.production.sample

+# This is a sample configuration file. You can generate your configuration
+# with the `rake mastodon:setup` interactive setup wizard, but to customize
+# your setup even further, you'll need to edit it manually. This sample does
+# not demonstrate all available configuration options. Please look at
+# https://docs.joinmastodon/admin/config/ for the full documentation.
+
+# Federation
+# ----------
+# This identifies your server and cannot be changed safely later
+# ----------
+LOCAL_DOMAIN=example.com
+
+# Redis
+# -----
+REDIS_HOST=localhost
+REDIS_PORT=6379
+
+# PostgreSQL
+# ----------
+DB_HOST=/var/run/postgresql
+DB_USER=mastodon
+DB_NAME=mastodon_production
+DB_PASS=
+DB_PORT=5432
+
+# ElasticSearch (optional)
+# ------------------------
+ES_ENABLED=true
+ES_HOST=localhost
+ES_PORT=9200
+
+# Secrets
+# -------
+# Make sure to use `rake secret` to generate secrets
+# -------
+SECRET_KEY_BASE=
+OTP_SECRET=
+
+# Web Push
+# --------
+# Generate with `rake mastodon:webpush:generate_vapid_key`
+# --------
+VAPID_PRIVATE_KEY=
+VAPID_PUBLIC_KEY=
+
+# Sending mail
+# ------------
+SMTP_SERVER=smtp.mailgun.org
+SMTP_PORT=587
+SMTP_LOGIN=
+SMTP_PASSWORD=
+SMTP_FROM_ADDRESS=notificatons@example.com
+
+# File storage (optional)
+# -----------------------
+S3_ENABLED=true
+S3_BUCKET=files.example.com
+AWS_ACCESS_KEY_ID=
+AWS_SECRET_ACCESS_KEY=
+S3_ALIAS_HOST=files.example.com