Update documentation (#2032)
Update documentation (#2032)

`manifestPlugin.opts` - is incorrect
`manifestPlugin.options` - correct :-)
rails/webpacker,rails/webpacker,rossta/webpacker,gauravtiwari/webpacker,rossta/webpacker,rossta/webpacker,gauravtiwari/webpacker,gauravtiwari/webpacker,rossta/webpacker