docs: document configuration options

README.md

@@ -2,3 +2,27 @@ Dash0 Node.js OpenTelemetry Distribution
 ========================================
 
 This is the Dash0 OpenTelemetry distribution for Node.js.
+It is primarily intended to be used by the [Dash0 Kubernetes operator](https://github.com/dash0hq/dash0-operator) to
+instrument Node.js workloads with OpenTelemetry.
+
+Configuration
+-------------
+
+### <a id="DASH0_AUTOMATIC_SERVICE_NAME">DASH0_AUTOMATIC_SERVICE_NAME</a>
+
+If no `OTEL_SERVICE_NAME` has been set, a service name is automatically derived by reading the main `package.json` file
+(if it is present) as `${packageJson.name}@${packageJson.version}`.
+This can be disabled either by setting `OTEL_SERVICE_NAME` or by setting `DASH0_AUTOMATIC_SERVICE_NAME=false`.
+
+### <a id="DASH0_DEBUG">DASH0_DEBUG</a>
+
+Additional debug logs can be enabled by setting `DASH0_DEBUG=true`.
+
+### <a id="DASH0_ENABLE_FS_INSTRUMENTATION">DASH0_ENABLE_FS_INSTRUMENTATION</a>
+
+By default, the instrumentation plug-in `@opentelemetry/instrumentation-fs` is disabled. Set `DASH0_ENABLE_FS_INSTRUMENTATION=true` to enable spans for file system access.
+
+### <a id="DASH0_OTEL_COLLECTOR_BASE_URL">DASH0_OTEL_COLLECTOR_BASE_URL</a>
+
+The base URL of the OpenTelemetry collector that the distribution will send data to.
+It defaults to `http://dash0-operator-opentelemetry-collector.dash0-operator-system.svc.cluster.local:4318`.