Rosa Bug --env flag should pop a warning if there is no match for available env.

[MrSantamaria]

`

rosa login --env prod --govcloud --admin --region us-gov-west-1
To login to your Red Hat account, get an offline access token at
? Copy the token and paste it here:
`
This doesn't show a link to get token or throw an error that "prod" is not recognized.

`

rosa login --env production --govcloud --admin --region us-gov-west-1
To login to your Red Hat account, get an offline access token at https://api-admin.openshiftusgov.com/auth
? Copy the token and paste it here:
`
The proper value is production.

[hunterkepley]

Will be addressing soon, thanks for submitting this issue