Rails Documentation of hash options

Is it just me or is the current rails documentation severely lacking
when it comes to documenting all the various hash options can be sent to
many rails methods. Things like html_options, session_options, etc. Is
an easier way to figure out the available options, other than reading
rails source. If so I¹m all ears. If not I am not just complaining I¹ll
up my sleeves and help document them if pointed in the right direction.