DOC: first cut documenting global configs. Close #479
DOC: first cut documenting global configs. Close #479

adamobeng/ibis,Supermem/ibis,korotkyn/ibis,glenioborges/ibis,koverholt/ibis,cloudera/ibis,glenioborges/ibis,mahantheshhv/ibis,deepfield/ibis,cpcloud/ibis,dboyliao/ibis,ibis-project/ibis,wesm/ibis,cpcloud/ibis,mariusvniekerk/ibis,adamobeng/ibis,cloudera/ibis,cpcloud/ibis,wesm/ibis,koverholt/ibis,laserson/ibis,mariusvniekerk/ibis,ibis-project/ibis,ashhher3/ibis,ibis-project/ibis,deepfield/ibis,mariusvniekerk/ibis,dboyliao/ibis,ashhher3/ibis,mahantheshhv/ibis,ashhher3/ibis,mahantheshhv/ibis,mahantheshhv/ibis,adamobeng/ibis,aslihandincer/ibis,glenioborges/ibis,korotkyn/ibis,laserson/ibis,deepfield/ibis,aslihandincer/ibis,laserson/ibis,koverholt/ibis,aslihandincer/ibis,Supermem/ibis,Supermem/ibis,Supermem/ibis,mariusvniekerk/ibis,dboyliao/ibis,aslihandincer/ibis,ashhher3/ibis,glenioborges/ibis,wesm/ibis,korotkyn/ibis,korotkyn/ibis,adamobeng/ibis,cloudera/ibis,laserson/ibis,dboyliao/ibis,ibis-project/ibis,koverholt/ibis,deepfield/ibis,cpcloud/ibis