feat(docs): Revamp README

README.md

@@ -1,7 +1,7 @@
 # railway-chord
 
-Centralized logging for [Railway.app](https://railway.app) projects, powered
-by [Vector](https://vector.dev/).
+[Vector](https://vector.dev/) log egress for [Railway.app](https://railway.app)
+projects.
 
 _railway-chord_ pipes the log stream from Railway's GraphQL API into Vector.
 This gives you **project-wide** centralized logging on Railway. For each Railway
@@ -20,7 +20,25 @@ the instructions in the link.
 
 The button above will deploy _railway-chord_ on Railway. You will be prompted to
 set some required environment variables; there is no additional configuration
-required beyond this.
+required beyond this. Log sinks are automatically configured based on the
+presence of required environment variables of each provider, i.e. setting a
+`DATADOG_TOKEN` will enable Datadog, and so on.
+
+### Datadog
+
+To enable Datadog logs, set the `DATADOG_TOKEN` service variable.
+
+There is an optional `DATADOG_SITE` setting if your Datadog account is hosted
+on a different Datadog instance (defaults to `datadoghq.com`).
+
+### Logtail
+
+To enable Logtail, set the `LOGTAIL_TOKEN` service variable.
+
+### `stdout`
+
+To enable logging to `stdout`, set `ENABLE_STDOUT=true`. This will output all
+enabled project's logs into _railway-chord_'s `stdout`.
 
 ### Project IDs
 
@@ -34,6 +52,32 @@ Railway's Dashboard -> Project -> Settings -> General.
 RAILWAY_PROJECT_IDS="XXXXXXXX-XXXX-XXXX-XXXX-XXXXXXXXXXXX,XXXXXXXX-XXXX-XXXX-XXXX-XXXXXXXXXXXX"
 ```
 
+### Log Enrichment
+
+_railway-chord_ will inject a `railway` object into the logs sent to the provider
+containing the deployment/plugin ID and name.
+
+#### Example:
+
+```json
+{
+  "railway": {
+    "id": "XXXXXXXX-XXXX-XXXX-XXXX-XXXXXXXXXXXX",
+    "name": "app.up.railway.app",
+    "type": "DEPLOYMENT"
+  }
+}
+```
+
+### Railway API Rate Limit
+
+Railway's Public API currently has a [rate limit of 1,000 requests daily](https://docs.railway.app/reference/public-api#rate-limits). _railway-chord_ will make ~100 requests every 24 hours for each project enabled.
+Work is underway to reduce the amount of requests _railway-chord_ is making (see
+[railway-chord#3](https://github.com/half0wl/railway-chord/issues/3)).
+
+Be careful about this if you're using Railway's API for something else - _railway-chord_
+will eat into your rate limit!
+
 ## Adding Vector sinks
 
 ### Request for new sinks
@@ -90,11 +134,13 @@ the newly-created config created above, passing the required API key into it:
 | ----------- | ----------- |
 | `RAILWAY_API_TOKEN` | **Required**. Railway API token. |
 | `RAILWAY_PROJECT_IDS` | **Required**. A comma-separated list of Railway Project IDs. |
-| `LOGTAIL_TOKEN` | **Required**. Logtail token. |
+| `LOGTAIL_TOKEN` | Optional. Logtail token. |
+| `DATADOG_TOKEN` | Optional. Datadog API token. |
+| `DATADOG_SITE` | Optional. Datadog site setting. Defaults to `datadoghq.com`. |
+| `ENABLE_STDOUT` | Optional. Enable Vector logging to stdout. |
 | `RAILWAY_API_HTTP_ENDPOINT` | Optional. Railway's HTTP GQL Endpoint. Defaults to `https://backboard.railway.app/graphql/v2`. |
 | `RAILWAY_WS_HTTP_ENDPOINT` | Optional. Railway's WebSockets GQL Endpoint. Defaults to `wss://backboard.railway.app/graphql/v2`. |
 | `VECTOR_BIN_PATH` | Optional. Path to Vector binary. Defaults to path defined in Docker build. You do not need to set this. |
-| `VECTOR_CFG_PATH` | Optional. Path to Vector configuration. Defaults to path defined in Docker build. You do not need to set this. |
 
 ## License