[FIX] doc: json rpc example

Could crash if note was note installed.
Add example of parameters to connect to the database

Closes #24085

doc/howtos/backend.rst

@@ -1709,12 +1709,19 @@ JSON-RPC Library
 ----------------
 
 The following example is a Python 3 program that interacts with an Odoo server
-with the standard Python libraries ``urllib.request`` and ``json``::
+with the standard Python libraries ``urllib.request`` and ``json``. This
+example assumes the **Productivity** app (``note``) is installed::
 
     import json
     import random
     import urllib.request
 
+    HOST = 'localhost'
+    PORT = 8069
+    DB = 'openacademy'
+    USER = 'admin'
+    PASS = 'admin'
+
     def json_rpc(url, method, params):
         data = {
             "jsonrpc": "2.0",
@@ -1725,7 +1732,7 @@ with the standard Python libraries ``urllib.request`` and ``json``::
         req = urllib.request.Request(url=url, data=json.dumps(data).encode(), headers={
             "Content-Type":"application/json",
         })
-        reply = json.load(urllib.request.urlopen(req))
+        reply = json.loads(urllib.request.urlopen(req).read().decode('UTF-8'))
         if reply.get("error"):
             raise Exception(reply["error"])
         return reply["result"]