fix: restore missing architecture diagram in README (#2125)

* Update link

* Thingsboard -> ThingsBoard

Author: iamkaran

README.md

@@ -25,7 +25,7 @@ Curious how the ThingsBoard IoT Gateway works in action?
 
 ---
 
-[![What is ThingsBoard IoT Gateway?](https://thingsboard.io/images/gateway/python-gateway-animd-ff.svg)](https://thingsboard.io/docs/iot-gateway/what-is-iot-gateway/)
+[![What is ThingsBoard IoT Gateway?](https://img.thingsboard.io/gateway/python-gateway-animd-ff.svg)](https://thingsboard.io/docs/iot-gateway/what-is-iot-gateway/)
 
 ## 🔌 Gateway Features
 
@@ -85,7 +85,7 @@ The IoT Gateway is implemented in **Python**, allowing powerful extension and cu
 
 - **Custom connectors** let you interface with new devices or services.
 - **Custom converters** allow transformation of incoming messages to a ThingsBoard-compatible format.
-- The Gateway provides simple integration APIs, and encapsulates common Thingsboard related tasks: device provisioning, local data persistence and delivery, message converters and other.  
+- The Gateway provides simple integration APIs, and encapsulates common ThingsBoard related tasks: device provisioning, local data persistence and delivery, message converters and other.  
 
 > Ideal for edge use cases where flexibility and protocol diversity are key.