Update maintenance.rst
Update maintenance.rst

Added: How to create a compressed backup.
jmvasquez/redashtest,denisov-vlad/redash,hudl/redash,akariv/redash,vishesh92/redash,amino-data/redash,rockwotj/redash,chriszs/redash,moritz9/redash,crowdworks/redash,akariv/redash,alexanderlz/redash,stefanseifert/redash,getredash/redash,alexanderlz/redash,guaguadev/redash,rockwotj/redash,EverlyWell/redash,EverlyWell/redash,jmvasquez/redashtest,jmvasquez/redashtest,pubnative/redash,EverlyWell/redash,getredash/redash,44px/redash,moritz9/redash,easytaxibr/redash,denisov-vlad/redash,denisov-vlad/redash,M32Media/redash,moritz9/redash,akariv/redash,chriszs/redash,easytaxibr/redash,pubnative/redash,44px/redash,getredash/redash,ninneko/redash,denisov-vlad/redash,getredash/redash,M32Media/redash,amino-data/redash,guaguadev/redash,stefanseifert/redash,pubnative/redash,alexanderlz/redash,ninneko/redash,crowdworks/redash,alexanderlz/redash,rockwotj/redash,imsally/redash,easytaxibr/redash,akariv/redash,amino-data/redash,vishesh92/redash,guaguadev/redash,ninneko/redash,amino-data/redash,moritz9/redash,stefanseifert/redash,jmvasquez/redashtest,imsally/redash,guaguadev/redash,stefanseifert/redash,useabode/redash,ninneko/redash,rockwotj/redash,crowdworks/redash,chriszs/redash,easytaxibr/redash,stefanseifert/redash,easytaxibr/redash,imsally/redash,hudl/redash,M32Media/redash,vishesh92/redash,useabode/redash,imsally/redash,44px/redash,chriszs/redash,denisov-vlad/redash,ninneko/redash,hudl/redash,pubnative/redash,44px/redash,guaguadev/redash,pubnative/redash,useabode/redash,hudl/redash,jmvasquez/redashtest,crowdworks/redash,akariv/redash,vishesh92/redash,M32Media/redash,EverlyWell/redash,useabode/redash,getredash/redash