docs: Added headers in Code Guide

Author: IvanildoBarauna

README.md

@@ -53,10 +53,13 @@ from api_to_dataframe import ClientBuilder, RetryStrategies
 
 # Create a client for the API without retry strategy and default timeout (5 seconds)
 client = ClientBuilder(endpoint="https://api.example.com")
-# or with LinearStrategy (In development, actually don't nothing)
-client = ClientBuilder(endpoint="https://api.example.com", retry_strategy=RetryStrategies.LinearStrategy)
-# if you can define timeout, use: (default is 5 seconds)
-client = ClientBuilder(endpoint="https://api.example.com", retry_strategy=RetryStrategies.LinearStrategy, timeout=10)
+# if you can define timeout, use: (default is 5 seconds), with LinearStrategy (In development, actually don't nothing) and set headers:
+headers = {
+    "application_name": "api_to_dataframe"
+}
+client = ClientBuilder(endpoint="https://api.example.com", retry_strategy=RetryStrategies.LinearStrategy, timeout=10, headers=headers)
+
+### timeout, retry_strategy and headers are opcionals parameters 
 
 # Get data from the API
 data = client.get_api_data()