Tweak removal of redundant extensions property

Author: Chuxel

containers/debian-9-git/.devcontainer/devcontainer.json

@@ -15,12 +15,9 @@
 	// Uncomment the next line if you want to publish any ports.
 	// "appPort": [],
 
-	// Uncomment the next line to automatically install extensions.
-	// "extensions": [ "eamodio.gitlens" ],
-
 	// Uncomment the next line if you want to add in default container specific settings.json values
 	// "settings":  { "workbench.colorTheme": "Quiet Light" },
 
-	// Uncomment the next line to run commands after the container is created.
-	// "postCreateCommand": "uname -a",
+	// Add the IDs of any extensions you want installed in the array below.
+	"extensions": []
 }