Update serverless docs

Serverless/lambda-async.md

@@ -1,4 +1,4 @@
-Example how to use logzio-nodejs inside an async lambda
+## Example how to use logzio-nodejs inside an async lambda
 
 ```
 var logger = require('logzio-nodejs').createLogger({
@@ -24,3 +24,17 @@ exports.handler = async function(event,context) {
 	return context
 };
 ```
+
+## Usage with sendAndClose with callback
+The `sendAndClose` method can accept a callback function. This method sends any remaining log messages and then closes the logger. The callback function will be called once the remaining messages are sent.
+
+```javascript
+logger.sendAndClose(function(err) {
+    if (err) {
+        console.error('Error sending final logs:', err);
+    } else {
+        console.log('Final logs sent successfully');
+    }
+});
+```
+By using the callback option, you can effectively manage and monitor the log transmission process, ensuring that you are aware of any issues or confirming successful log deliveries.

Serverless/lambda-sync.md

@@ -1,4 +1,4 @@
-Example on how to use logzio-nodejs inside a sync lambda
+## Example on how to use logzio-nodejs inside a sync lambda
 
 ```
 var logger = require('logzio-nodejs').createLogger({
@@ -17,3 +17,16 @@ exports.handler = function(event,context,callback) {
         logger.sendAndClose(callback)
 };
 ```
+## Usage with sendAndClose with callback
+The `sendAndClose` method can accept a callback function. This method sends any remaining log messages and then closes the logger. The callback function will be called once the remaining messages are sent.
+
+```javascript
+logger.sendAndClose(function(err) {
+    if (err) {
+        console.error('Error sending final logs:', err);
+    } else {
+        console.log('Final logs sent successfully');
+    }
+});
+```
+By using the callback option, you can effectively manage and monitor the log transmission process, ensuring that you are aware of any issues or confirming successful log deliveries.