docs: docs: Add user instructions for STAC_ITEM_LIMIT env variable

Author: Yuri Zmytrakov

CHANGELOG.md

@@ -8,6 +8,7 @@ and this project adheres to [Semantic Versioning](http://semver.org/spec/v2.0.0.
 
 ## [Unreleased]
 
+- Added default environment variable `STAC_ITEM_LIMIT` to SFEOS for result limiting of returned items and STAC collections [#419](https://github.com/stac-utils/stac-fastapi-elasticsearch-opensearch/pull/419)
 
 ## [v6.2.0] - 2025-08-27
 

README.md

@@ -227,6 +227,7 @@ You can customize additional settings in your `.env` file:
 | `RAISE_ON_BULK_ERROR`        | Controls whether bulk insert operations raise exceptions on errors. If set to `true`, the operation will stop and raise an exception when an error occurs. If set to `false`, errors will be logged, and the operation will continue. **Note:** STAC Item and ItemCollection validation errors will always raise, regardless of this flag. | `false` | Optional |
 | `DATABASE_REFRESH`           | Controls whether database operations refresh the index immediately after changes. If set to `true`, changes will be immediately searchable. If set to `false`, changes may not be immediately visible but can improve performance for bulk operations. If set to `wait_for`, changes will wait for the next refresh cycle to become visible. | `false` | Optional |
 | `ENABLE_TRANSACTIONS_EXTENSIONS` | Enables or disables the Transactions and Bulk Transactions API extensions. If set to `false`, the POST `/collections` route and related transaction endpoints (including bulk transaction operations) will be unavailable in the API. This is useful for deployments where mutating the catalog via the API should be prevented. | `true` | Optional |
+| `STAC_ITEM_LIMIT` | Sets the environment variable for result limiting to SFEOS for the number of returned items and STAC collections. | `10` | Optional |
 
 > [!NOTE]
 > The variables `ES_HOST`, `ES_PORT`, `ES_USE_SSL`, `ES_VERIFY_CERTS` and `ES_TIMEOUT` apply to both Elasticsearch and OpenSearch backends, so there is no need to rename the key names to `OS_` even if you're using OpenSearch.