Add migrations steps and Option reference

Author: xrmx

docs/_edot-sdks/python/migration.md

@@ -67,3 +67,76 @@ EDOT Python does not implement [span compression](https://www.elastic.co/guide/e
 ### Breakdown metrics
 
 EDOT Python is not sending metrics that power the [Breakdown metrics](https://www.elastic.co/guide/en/apm/guide/current/data-model-metrics.html#_breakdown_metrics).
+
+## Migration steps
+
+- remove any configuration and setup code needed by Elastic APM Python Agent from your application source code.
+- migrate any eventual usage of Elastic APM Python Agent API for manual instrumentation with OpenTelemetry API in the application source code.
+- follow [setup documentation](setup/index) on how to install and configure EDOT Python
+
+## Option reference
+
+This list contains Elastic APM Python agent configuration options that can be migrated to EDOT Python configuration because they have an equivalent in OpenTelemetry:
+
+<!-- keep these sorted -->
+* [api_key](#api_key)
+* [enabled](#enabled)
+* [environment](#environment)
+* [global_labels](#global_labels)
+* [metrics_interval](#metrics_interval)
+* [secret_token](#secret_token)
+* [server_url](#server_url)
+* [service_name](#service_name)
+* [service_version](#service_version)
+
+### `api_key`
+
+The Elastic [`api_key`](https://www.elastic.co/guide/en/apm/agent/python/current/configuration.html#config-api-key) option corresponds to the OpenTelemetry [OTEL_EXPORTER_OTLP_HEADERS](https://opentelemetry.io/docs/concepts/sdk-configuration/otlp-exporter-configuration/#otel_exporter_otlp_headers) option.
+
+For example:`OTEL_EXPORTER_OTLP_HEADERS="Authorization=ApiKey an_api_key"`.
+
+### `enabled`
+
+The Elastic [`enabled`](https://www.elastic.co/guide/en/apm/agent/python/current/configuration.html#config-enabled) option corresponds to the OpenTelemetry [OTEL_SDK_DISABLED](https://opentelemetry.io/docs/specs/otel/configuration/sdk-environment-variables/#general-sdk-configuration) option.
+
+### `environment`
+
+The Elastic [`environment`](https://www.elastic.co/guide/en/apm/agent/python/current/configuration.html#config-environment) option corresponds to setting the `deployment.environment.name` key in [OTEL_RESOURCE_ATTRIBUTES](https://opentelemetry.io/docs/concepts/sdk-configuration/general-sdk-configuration/#otel_resource_attributes).
+
+For example: `OTEL_RESOURCE_ATTRIBUTES=deployment.environment.name=testing`.
+
+### `global_labels`
+
+The Elastic [`global_labels`](https://www.elastic.co/guide/en/apm/agent/python/current/configuration.html#config-global-labels) option corresponds to adding `key=value` comma separated pairs in [OTEL_RESOURCE_ATTRIBUTES](https://opentelemetry.io/docs/concepts/sdk-configuration/general-sdk-configuration/#otel_resource_attributes).
+
+For example: `OTEL_RESOURCE_ATTRIBUTES=alice=first,bob=second`. Such labels will result in labels.key=value attributes on the server, e.g. labels.alice=first
+
+### `metrics_interval`
+
+The Elastic [`metrics_interval`](https://www.elastic.co/guide/en/apm/agent/python/current/configuration.html#config-metrics_interval) corresponds to the OpenTelemetry [OTEL_METRIC_EXPORT_INTERVAL](https://opentelemetry.io/docs/specs/otel/configuration/sdk-environment-variables/#periodic-exporting-metricreader) option.
+
+For example: `OTEL_METRIC_EXPORT_INTERVAL=30000`.
+
+### `secret_token`
+
+The Elastic [`secret_token`](https://www.elastic.co/guide/en/apm/agent/python/current/configuration.html#config-secret-token) option corresponds to the OpenTelemetry [OTEL_EXPORTER_OTLP_HEADERS](https://opentelemetry.io/docs/concepts/sdk-configuration/otlp-exporter-configuration/#otel_exporter_otlp_headers) option.
+
+For example: `OTEL_EXPORTER_OTLP_HEADERS="Authorization=Bearer an_apm_secret_token"`.
+
+### `server_url`
+
+The Elastic [`server_url`](https://www.elastic.co/guide/en/apm/agent/python/current/configuration.html#config-server-url) option corresponds to the OpenTelemetry [`OTEL_EXPORTER_OTLP_ENDPOINT`](https://opentelemetry.io/docs/concepts/sdk-configuration/otlp-exporter-configuration/#otel_exporter_otlp_endpoint) option.
+
+### `service_name`
+
+The Elastic [`service_name`](https://www.elastic.co/guide/en/apm/agent/python/current/configuration.html#config-service-name) option corresponds to the OpenTelemetry [OTEL_SERVICE_NAME](https://opentelemetry.io/docs/concepts/sdk-configuration/general-sdk-configuration/#otel_service_name) option.
+
+The service name value can also be set using [OTEL_RESOURCE_ATTRIBUTES](https://opentelemetry.io/docs/concepts/sdk-configuration/general-sdk-configuration/#otel_resource_attributes).
+
+For example: `OTEL_RESOURCE_ATTRIBUTES=service.name=myservice`. If `OTEL_SERVICE_NAME` is set, it takes precedence over the resource attribute.
+
+### `service_version`
+
+The Elastic [`service_version`](https://www.elastic.co/guide/en/apm/agent/python/current/configuration.html#config-service-version) option corresponds to setting the `service.version` key in [OTEL_RESOURCE_ATTRIBUTES](https://opentelemetry.io/docs/concepts/sdk-configuration/general-sdk-configuration/#otel_resource_attributes).
+
+For example: `OTEL_RESOURCE_ATTRIBUTES=service.version=1.2.3`.