534 update config options docs

Based on #693, see previous discussion there. 

@vitorbaptista I've created the PR because I could not push more changes to yours becasue it was based on your repo.

@seanh All looks good, I've cleaned up some options and rearranged the sections more logically. Perhaps the most controversial change is moving the authorization config options to the configuration docs and include them back on the authorizations page to avoid duplication (see 01cd2de for details). I'll try it on RTD to make sure it works