updated python datasources note to reflect preference for setting environ variable over editing settings.py
updated python datasources note to reflect preference for setting environ variable over editing settings.py

imsally/redash,getredash/redash,akariv/redash,M32Media/redash,ninneko/redash,denisov-vlad/redash,imsally/redash,easytaxibr/redash,denisov-vlad/redash,chriszs/redash,ninneko/redash,hudl/redash,ninneko/redash,denisov-vlad/redash,moritz9/redash,chriszs/redash,M32Media/redash,rockwotj/redash,amino-data/redash,crowdworks/redash,jmvasquez/redashtest,pubnative/redash,pubnative/redash,pubnative/redash,hudl/redash,stefanseifert/redash,ninneko/redash,crowdworks/redash,useabode/redash,getredash/redash,guaguadev/redash,denisov-vlad/redash,getredash/redash,alexanderlz/redash,jmvasquez/redashtest,EverlyWell/redash,guaguadev/redash,moritz9/redash,crowdworks/redash,getredash/redash,vishesh92/redash,guaguadev/redash,chriszs/redash,jmvasquez/redashtest,alexanderlz/redash,alexanderlz/redash,ninneko/redash,getredash/redash,amino-data/redash,easytaxibr/redash,akariv/redash,vishesh92/redash,EverlyWell/redash,crowdworks/redash,stefanseifert/redash,easytaxibr/redash,rockwotj/redash,useabode/redash,akariv/redash,EverlyWell/redash,guaguadev/redash,easytaxibr/redash,easytaxibr/redash,moritz9/redash,vishesh92/redash,akariv/redash,stefanseifert/redash,rockwotj/redash,alexanderlz/redash,jmvasquez/redashtest,44px/redash,akariv/redash,44px/redash,pubnative/redash,pubnative/redash,stefanseifert/redash,44px/redash,amino-data/redash,vishesh92/redash,imsally/redash,stefanseifert/redash,rockwotj/redash,useabode/redash,M32Media/redash,44px/redash,M32Media/redash,moritz9/redash,amino-data/redash,chriszs/redash,useabode/redash,guaguadev/redash,denisov-vlad/redash,hudl/redash,imsally/redash,jmvasquez/redashtest,EverlyWell/redash,hudl/redash