Update installation instructions re: unmet peer dependencies (#1496)
Update installation instructions re: unmet peer dependencies (#1496)

See discussion in https://github.com/rails/webpacker/issues/1078
rails/webpacker,rails/webpacker,gauravtiwari/webpacker,rossta/webpacker,gauravtiwari/webpacker,gauravtiwari/webpacker,rossta/webpacker,rossta/webpacker,rossta/webpacker