✨ Add documentation for the Kafka node

docs/nodes/nodes-library/nodes/Kafka/README.md

@@ -0,0 +1,90 @@
+---
+permalink: /nodes/n8n-nodes-base.kafka
+description: Learn how to use the Kafka node in n8n
+---
+
+# Kafka
+
+[Kafka](https://kafka.apache.org/) is an open-source distributed event streaming platform that one can use for high-performance data pipelines, streaming analytics, data integration, and mission-critical applications.
+
+::: tip 🔑 Credentials
+You can find authentication information for this node [here](../../../credentials/Kafka/README.md).
+:::
+
+## Example Usage
+
+This workflow allows you to send updates about the position of the ISS every minute to a topic in Kafka using the Kafka node. You can also find the [workflow](https://n8n.io/workflows/750) on n8n.io. This example usage workflow uses the following nodes.
+- [Cron](../../core-nodes/Cron/README.md)
+- [HTTPRequest](../../core-nodes/HTTPRequest/README.md)
+- [Set](../../core-nodes/Set/README.md)
+- [Kafka]()
+
+The final workflow should look like the following image.
+
+![A workflow with the Kafka node](./workflow.png)
+
+### 1. Cron node
+
+The Cron node will trigger the workflow every minute.
+
+1. Click on ***Add Cron Time***.
+2. Select 'Every Minute' from the ***Mode*** dropdown list.
+3. Click on ***Execute Node*** to run the node.
+
+In the screenshot below, you will notice that the Cron node is configured to trigger the workflow every minute.
+
+![Using the Cron node to trigger the workflow every minute](./Cron_node.png)
+
+### 2. HTTP Request node (GET)
+
+This node will make a GET request to `https://api.wheretheiss.at/v1/satellites/25544/positions` to fetch the position of the ISS. This information gets passed on to the next node in the workflow.
+::: v-pre
+1. Enter `https://api.wheretheiss.at/v1/satellites/25544/positions` in the ***URL*** field. 
+2. Click on the ***Add Parameter*** button in the ***Query Parameters*** section.
+3. Enter `timestamps` in the ***Name*** field.
+4. Click on the gears icon next to the ***Value*** field and click on ***Add Expression***.
+5. Enter the following expression: `{{Date.now();}}`. This expression will return the current timestamp.
+6. Click on ***Execute Node*** to run the node.
+:::
+In the screenshot below, you will notice that the node makes a GET request to the API and returns the information about the location of the ISS.
+
+![Using the HTTP Request node to get the information about the location of the ISS](./HTTPRequest_node.png)
+
+### 3. Set node
+
+We will use the Set node to set the data coming from the previous node. This data gets passed on to the next node in the workflow.
+::: v-pre
+1. Click on ***Add Value*** and select 'String' from the dropdown list.
+2. Enter `Name` in the ***Name*** field.
+3. Click on the gears icon next to the ***Value*** field and click on ***Add Expression***.
+4. Select the following in the ***Variable Selector*** section: Nodes > HTTP Request > Output Data > JSON > 0 > name. You can also add the following expression: `{{$node["HTTP Request"].json["0"]["name"]}}`.
+5. Click on ***Add Value*** and select 'Number' from the dropdown list.
+6. Enter `Latitude` in the ***Name*** field.
+7. Click on the gears icon next to the ***Value*** field and click on ***Add Expression***.
+8. Select the following in the ***Variable Selector*** section: Nodes > HTTP Request > Output Data > JSON > 0 > latitude. You can also add the following expression: `{{$node["HTTP Request"].json["0"]["latitude"]}}`.
+9. Click on ***Add Value*** and select 'Number' from the dropdown list.
+10. Enter `Longitude` in the ***Name*** field.
+11. Click on the gears icon next to the ***Value*** field and click on ***Add Expression***.
+12. Select the following in the ***Variable Selector*** section: Nodes > HTTP Request > Output Data > JSON > 0 > longitude. You can also add the following expression: `{{$node["HTTP Request"].json["0"]["longitude"]}}`.
+13. Click on ***Add Value*** and select 'Number' from the dropdown list.
+14. Enter `Timestamp` in the ***Name*** field.
+15. Click on the gears icon next to the ***Value*** field and click on ***Add Expression***.
+16. Select the following in the ***Variable Selector*** section: Nodes > HTTP Request > Output Data > JSON > 0 > timpestamp. You can also add the following expression: `{{$node["HTTP Request"].json["0"]["timestamp"]}}`.
+17. Toggle ***Keep Only Set*** to `true`.
+18. Click on ***Execute Node*** to run the node.
+:::
+In the screenshot below, you will notice that the node uses the data from the previous node and returns the data that we set for the workflow.
+
+![Using the Set node to set the data](./Set_node.png)
+
+### 4. Kafka node
+
+This node will send the data from the previous node to the `iss-position` topic in Kafka. If you have created a topic with a different name in Kafka, use that topic name instead.
+
+1. First of all, you'll have to enter credentials for the Kafka node. You can find out how to do that [here](../../../credentials/Kafka/README.md).
+2. Enter the name of the topic in the ***Topic*** field.
+3. Click on ***Execute Node*** to run the node.
+
+In the screenshot below, you will notice that the node sends the data from the previous node to the `iss-position` topic in Kafka.
+
+![Using the Kafka node to send the data to a topic](./Kafka_node.png)