Use stable docs

platformio/app.py

@@ -46,7 +46,7 @@ DEFAULT_SETTINGS = {
     },
     "enable_telemetry": {
         "description": (
-            "Telemetry service <http://docs.platformio.org/en/latest/"
+            "Telemetry service <http://docs.platformio.org/en/stable/"
             "userguide/cmd_settings.html?#enable-telemetry> (Yes/No)"),
         "value": True
     },