Update supportedFolders.js
Update supportedFolders.js

in polymer-tools dist folder name is "build"
vscode-icons/vscode-icons,JimiC/vscode-icons,vscode-icons/vscode-icons,JimiC/vscode-icons,robertohuertasm/vscode-icons,olzaragoza/vscode-icons,jens1o/vscode-icons