websocket: Updated Kconfig to use 'echo.websocket.events' echo server

Updated README to show how to run websocket echo server using Flask

Merges https://github.com/espressif/esp-idf/pull/8262

examples/protocols/websocket/README.md

@@ -36,7 +36,7 @@ I (4472) tcpip_adapter: eth ip: 192.168.2.137, mask: 255.255.255.0, gw: 192.168.
 I (4472) example_connect: Connected to Ethernet
 I (4472) example_connect: IPv4 address: 192.168.2.137
 I (4472) example_connect: IPv6 address: fe80:0000:0000:0000:bedd:c2ff:fed4:a92b
-I (4482) WEBSOCKET: Connecting to ws://echo.websocket.org...
+I (4482) WEBSOCKET: Connecting to ws://echo.websocket.events...
 I (5012) WEBSOCKET: WEBSOCKET_EVENT_CONNECTED
 I (5492) WEBSOCKET: Sending hello 0000
 I (6052) WEBSOCKET: WEBSOCKET_EVENT_DATA
@@ -56,3 +56,35 @@ W (9162) WEBSOCKET: Received=hello 0003
 
 ```
 
+
+## Python Flask echo server
+
+By default, the `ws://echo.websocket.events` endpoint is used. You can setup a Python websocket echo server locally and try the `ws://<your-ip>:5000` endpoint. To do this, install Flask-sock Python package
+
+```
+pip install flask-sock
+```
+
+and start a Flask websocket echo server locally by executing the following Python code:
+
+```python
+from flask import Flask
+from flask_sock import Sock
+
+app = Flask(__name__)
+sock = Sock(app)
+
+
+@sock.route('/')
+def echo(ws):
+    while True:
+        data = ws.receive()
+        ws.send(data)
+
+
+if __name__ == '__main__':
+    # To run your Flask + WebSocket server in production you can use Gunicorn:
+    # gunicorn -b 0.0.0.0:5000 --workers 4 --threads 100 module:app
+    app.run(host="0.0.0.0", debug=True)
+```
+

examples/protocols/websocket/main/Kconfig.projbuild

@@ -16,7 +16,7 @@ menu "Example Configuration"
     config WEBSOCKET_URI
         string "Websocket endpoint URI"
         depends on WEBSOCKET_URI_FROM_STRING
-        default "ws://echo.websocket.org"
+        default "ws://echo.websocket.events"
         help
             URL of websocket endpoint this example connects to and sends echo