get rid of annoying extensions json prompt

.vscode/extensions.json

@@ -1,11 +0,0 @@
-{
-    // See http://go.microsoft.com/fwlink/?LinkId=827846
-    // for the documentation about the extensions.json format
-    "recommendations": [
-        "pioarduino.pioarduino-ide",
-        "platformio.platformio-ide"
-    ],
-    "unwantedRecommendations": [
-        "ms-vscode.cpptools-extension-pack"
-    ]
-}