Edited development build command for webpack

[GurpreetSingh5]

Edited development build command for webpack, to resolve following error

"Module not found: Error: Can't resolve 'dist/bundle.js' WARNING in configuration The 'mode' option has not been set, webpack will fallback to 'production' for this value. Set 'mode' option to 'development' or 'production' to enable defaults for each environment. You can also set it to 'none' to disable any default behavior."