add readme for addons folder

Author: spdeepak

addons/README.md

@@ -0,0 +1,100 @@
+# 🧩 FlowTracker Addons
+
+This directory contains official extensions for the **[FlowTracker](https://github.com/spdeepak/flowtracker)** library.
+
+### Why are these separate?
+To keep the core `flowtracker` library lightweight and dependency-free.
+*   **Core Library:** Zero heavy dependencies. Just standard Go.
+*   **Addons:** May require heavy SDKs (Kafka, OpenTelemetry).
+
+By using a **Multi-Module** architecture, you only download the dependencies for the specific exporters you actually use.
+
+---
+
+## 📦 Available Addons
+
+| Addon                                            | Description | Dependencies |
+|:-------------------------------------------------| :--- | :--- |
+| **[Kafka Exporter](./confluent-kafka)** | Pushes trace data to an Apache Kafka topic. | `confluent-kafka-go` |
+| **[OpenTelemetry Bridge](./otel)**      | Sends traces to Jaeger, Grafana Tempo, Datadog, etc. | `go.opentelemetry.io` |
+
+---
+
+## 🚀 Installation
+
+Because these are separate Go modules, you must `go get` the specific addon you need.
+
+**Example: Installing the Kafka Exporter**
+```bash
+# 1. Get the core
+go get github.com/spdeepak/flowtracker
+
+# 2. Get the addon
+go get github.com/spdeepak/flowtracker/kafka-exporter
+```
+
+---
+
+## 🛠 General Usage
+
+All addons implement the standard `Exporter` interface defined in the core library. Usage is consistent across all extensions:
+
+```go
+package main
+
+import (
+    "github.com/spdeepak/flowtracker"
+    "github.com/spdeepak/flowtracker/kafka-exporter" // Import the addon
+)
+
+func main() {
+    // 1. Initialize the Addon
+    // (Refer to the specific addon's README for config details)
+    myExporter, _ := kafkaexporter.New(...)
+
+    // 2. Inject into Middleware
+    mw := flowtracker.NewMiddleware(
+        flowtracker.WithExporter(myExporter),
+    )
+
+    // 3. Run Server
+    http.ListenAndServe(":8080", mw(mux))
+}
+```
+
+---
+
+## 👩‍💻 Contributing a New Addon
+
+We welcome contributions! If you want to create a new exporter (e.g., for AWS S3, Elasticsearch, or Slack), follow these steps:
+
+1.  **Create a directory:**
+    ```bash
+    mkdir addons/my-new-exporter
+    cd addons/my-new-exporter
+    ```
+
+2.  **Initialize the Module:**
+    *Important: The module name must include the full path.*
+    ```bash
+    go mod init github.com/spdeepak/flowtracker/my-new-exporter
+    ```
+
+3.  **Develop Locally:**
+    In your `go.mod`, use a replace directive to point to the local core library during development:
+    ```go
+    require github.com/spdeepak/flowtracker v0.0.0
+    replace github.com/spdeepak/flowtracker => ../../flowtracker
+    ```
+
+4.  **Implement the Interface:**
+    Your struct must satisfy:
+    ```go
+    type Exporter interface {
+        Export(trace *flowtracker.Trace)
+    }
+    ```
+
+5.  **Release:**
+    When ready to merge, remove the `replace` directive. Release tags for addons must follow the pattern:
+    `addons/my-new-exporter/v0.0.1`