docs: Update node setup docs and runtime wiring

Clarify the validated first-run Ink node flow and simplify the env template defaults.
Align op-node, Compose, and Prometheus settings with the documented setup so startup checks, ports, and sidecar behavior match runtime behavior.

Author: Cruz Molina

.env.example

@@ -2,48 +2,49 @@
 #                                ↓ REQUIRED ↓                                 #
 ###############################################################################
 
-# Network to run the node on ("ink-mainnet", "ink-sepolia", etc.)
-NETWORK_NAME=ink-mainnet
+# Recommended first run: ink-sepolia + full
+NETWORK_NAME=ink-sepolia
 
-# Type of node to run ("full" or "archive"), note that "archive" is 10x bigger
-NODE_TYPE=archive
+# "full" starts from an empty datadir. "archive" downloads a network snapshot
+# during bedrock-init and needs much more disk.
+NODE_TYPE=full
 
-# L1 node that the op-node (Bedrock) will get chain data from
+# For a quick Sepolia smoke test, these public endpoints worked during docs
+# validation:
+# - https://ethereum-sepolia-rpc.publicnode.com
+# - https://ethereum-sepolia-beacon-api.publicnode.com
+# For a long-running node, use a provider with higher rate limits.
+
+# L1 execution RPC endpoint for the matching Ethereum network
 OP_NODE__RPC_ENDPOINT=
 
-# L1 beacon endpoint, you can setup your own or use Quicknode
+# L1 beacon API endpoint for the matching Ethereum network
 OP_NODE__L1_BEACON=
 
-# Type of RPC that op-node is connected to, see README
-OP_NODE__RPC_TYPE=quicknode
-
-# L2 RPC to compare your local node against (https://rpc-gel-sepolia.inkonchain.com for ink-sepolia or https://rpc-gel.inkonchain.com for ink-mainnet)
-HEALTHCHECK__REFERENCE_RPC_PROVIDER=https://rpc-gel.inkonchain.com
+# Use "basic" for generic providers. Other supported values are alchemy,
+# quicknode, and erigon.
+OP_NODE__RPC_TYPE=basic
 
+# L2 RPC used by the healthcheck sidecar for comparison.
+# The per-network env files provide defaults, and this value overrides them.
+# For ink-mainnet, switch this to https://rpc-gel.inkonchain.com
+HEALTHCHECK__REFERENCE_RPC_PROVIDER=https://rpc-gel-sepolia.inkonchain.com
 
 ###############################################################################
 #                                ↓ OPTIONAL ↓                                 #
 ###############################################################################
 
-# Feel free to customize your image tag if you want, uses "latest" by default
-# See here for all available images: https://hub.docker.com/u/ethereumoptimism
-IMAGE_TAG__DTL=
+# Optional image tag overrides for sidecars
 IMAGE_TAG__HEALTHCHECK=
 IMAGE_TAG__PROMETHEUS=
 IMAGE_TAG__GRAFANA=
 IMAGE_TAG__INFLUXDB=
-IMAGE_TAG__OP_GETH=
-IMAGE_TAG__OP_NODE=
 
-# Exposed server ports (must be unique)
-# See docker-compose.yml for default values
-PORT__DTL=
+# Exposed host ports (must be unique). Set these only if the defaults clash.
 PORT__HEALTHCHECK_METRICS=
 PORT__PROMETHEUS=
 PORT__GRAFANA=
 PORT__INFLUXDB=
-PORT__TORRENT_UI=
-PORT__TORRENT=
 PORT__OP_GETH_HTTP=
 PORT__OP_GETH_WS=
 PORT__OP_GETH_P2P=