Add lookup join example (#656)

Author: gwaramadze

managed/dynamic-configuration/README.md

@@ -79,3 +79,121 @@ The blob storage configuration is automatically injected only when `contentStore
 ## Learn More
 
 For complete details, check our [official documentation](https://quix.io/docs/quix-cloud/managed-services/dynamic-configuration.html).
+
+## Using with Quix Streams join_lookup
+
+The Dynamic Configuration Manager works seamlessly with Quix Streams' `join_lookup` feature to enrich streaming data with configuration data in real-time.
+
+### Basic Example
+
+Here's how to use Dynamic Configuration with `join_lookup` to enrich sensor data with device configurations:
+
+```python
+from quixstreams import Application
+from quixstreams.dataframe.joins.lookups import QuixConfigurationService
+
+# Initialize the application
+app = Application()
+
+# Create a lookup instance pointing to your configuration topic
+lookup = QuixConfigurationService(
+    topic=app.topic("device-configurations"),
+    app_config=app.config
+)
+
+# Create your main data stream
+sdf = app.dataframe(app.topic("sensor-data"))
+
+# Enrich sensor data with device configuration
+sdf = sdf.join_lookup(
+    lookup=lookup,
+    on="device_id",  # The field to match on
+    fields={
+        "device_name": lookup.json_field(
+            jsonpath="$.device.name",
+            type="device-config"
+        ),
+        "calibration_params": lookup.json_field(
+            jsonpath="$.calibration",
+            type="device-config"
+        ),
+        "firmware_version": lookup.json_field(
+            jsonpath="$.firmware.version",
+            type="device-config"
+        )
+    }
+)
+
+# Process the enriched data
+sdf = sdf.apply(lambda value: {
+    **value,
+    "device_info": f"{value['device_name']} (v{value['firmware_version']})"
+})
+
+# Output to destination topic
+sdf.to_topic(app.topic("enriched-sensor-data"))
+
+if __name__ == "__main__":
+    app.run()
+```
+
+### Advanced Configuration Matching
+
+You can also use custom key matching logic for more complex scenarios:
+
+```python
+def custom_key_matcher(value, key):
+    """Custom logic to determine configuration key"""
+    device_type = value.get("device_type", "unknown")
+    location = value.get("location", "default")
+    return f"{device_type}-{location}"
+
+# Use custom key matching
+sdf = sdf.join_lookup(
+    lookup=lookup,
+    on=custom_key_matcher,
+    fields={
+        "config": lookup.json_field(
+            jsonpath="$",
+            type="location-config"
+        )
+    }
+)
+```
+
+### Binary Configuration Support
+
+For non-JSON configurations (firmware files, calibration data, etc.):
+
+```python
+sdf = sdf.join_lookup(
+    lookup=lookup,
+    on="device_id",
+    fields={
+        "firmware_binary": lookup.bytes_field(
+            type="firmware"
+        ),
+        "calibration_data": lookup.bytes_field(
+            type="calibration"
+        )
+    }
+)
+```
+
+### How It Works
+
+1. **Configuration Updates**: When configurations are updated via the Dynamic Configuration API, lightweight Kafka events are published to your configuration topic.
+
+2. **Real-time Enrichment**: The `join_lookup` feature listens to these events, fetches the latest configuration content, and caches it locally.
+
+3. **Stream Enrichment**: As your main data stream processes records, `join_lookup` automatically enriches each record with the appropriate configuration data based on the matching key and timestamp.
+
+4. **Version Management**: The system automatically handles configuration versioning, ensuring that each record is enriched with the configuration version that was valid at the time the record was created.
+
+### Benefits
+
+- **Real-time Updates**: Configuration changes are immediately available to your streaming applications
+- **Large File Support**: Handle configuration files too large for direct Kafka streaming
+- **Version Control**: Automatic versioning ensures data consistency
+- **Performance**: Local caching minimizes API calls and latency
+- **Flexibility**: Support for both JSON and binary configuration content