Step Functions: add deprecation note for LOCAL_PORT_STEPFUNCTIONS (#1731)

Author: MEPalma

content/en/references/configuration.md

@@ -454,6 +454,7 @@ These configurations have already been removed and **won't have any effect** on
 | `LAMBDA_EVENT_SOURCE_MAPPING` | 4.0.0 | `v2` (default since [3.8.0](https://blog.localstack.cloud/localstack-release-v-3-8-0/#new-default-lambda-event-source-mapping-implementation)) \| `v1` | Feature flag to switch Lambda Event Source Mapping (ESM) implementations. |
 | `PROVIDER_OVERRIDE_STEPFUNCTIONS` | 4.0.0 | `v2` (default) \| `legacy` | The new LocalStack-native StepFunctions provider (v2) is active by default since LocalStack 3.0. |
 | `STEPFUNCTIONS_LAMBDA_ENDPOINT` | 4.0.0 | `default` | This is only supported for the `legacy` provider. URL to use as the Lambda service endpoint in Step Functions. By default this is the LocalStack Lambda endpoint. Use default to select the original AWS Lambda endpoint. |
+| `LOCAL_PORT_STEPFUNCTIONS` | 4.0.0 | `8083` (default) | This is only supported for the legacy provider. It defines the local port to which Step Functions traffic is redirected. By default, LocalStack routes Step Functions traffic to its internal runtime. Use this variable only if you need to redirect traffic to a different local Step Functions runtime. |
 | `S3_DIR` | 4.0.0 | `/path/to/root` | This was only supported for the `legacy_v2` provider. Configure a global parent directory that contains all buckets as sub-directories (`S3_DIR=/path/to/root`) or an individual directory that will get mounted as special bucket names (`S3_DIR=/path/to/root/bucket1:bucket1`). Only available for Localstack Pro.
 | `<SERVICE>_BACKEND` | 3.0.0 | `http://localhost:7577` |  Custom endpoint URL to use for a specific service, where `<SERVICE>` is the uppercase service name. |
 | `<SERVICE>_PORT_EXTERNAL` | 3.0.0 | `4567` | Port number to expose a specific service externally . `SQS_PORT_EXTERNAL`, e.g. , is used when returning queue URLs from the SQS service to the client. |