Guides: Mention that preferences are serialized in `Spree::Base`
Guides: Mention that preferences are serialized in `Spree::Base`

Fixes #6008

Hawaiideveloper/shoppingcart,madetech/spree,azclick/spree,jaspreet21anand/spree,welitonfreitas/spree,brchristian/spree,berkes/spree,berkes/spree,imella/spree,raow/spree,ahmetabdi/spree,patdec/spree,Engeltj/spree,lsirivong/spree,karlitxo/spree,calvinl/spree,orenf/spree,Hawaiideveloper/shoppingcart,grzlus/spree,rakibulislam/spree,JDutil/spree,jaspreet21anand/spree,karlitxo/spree,firman/spree,abhishekjain16/spree,grzlus/spree,shaywood2/spree,raow/spree,hifly/spree,Boomkat/spree,FadliKun/spree,jparr/spree,adaddeo/spree,softr8/spree,jspizziri/spree,mleglise/spree,fahidnasir/spree,hifly/spree,Ropeney/spree,patdec/spree,maybii/spree,DynamoMTL/spree,vcavallo/spree,rakibulislam/spree,zamiang/spree,SadTreeFriends/spree,DynamoMTL/spree,edgward/spree,keatonrow/spree,delphsoft/spree-store-ballchair,ahmetabdi/spree,DarkoP/spree,sliaquat/spree,caiqinghua/spree,lyzxsc/spree,grzlus/spree,tesserakt/clean_spree,rajeevriitm/spree,Boomkat/spree,softr8/spree,jparr/spree,builtbybuffalo/spree,Machpowersystems/spree_mach,locomotivapro/spree,alejandromangione/spree,trigrass2/spree,pulkit21/spree,agient/agientstorefront,siddharth28/spree,mleglise/spree,miyazawatomoka/spree,dandanwei/spree,sliaquat/spree,trigrass2/spree,reinaris/spree,APohio/spree,vmatekole/spree,pervino/spree,useiichi/spree,sfcgeorge/spree,zamiang/spree,alvinjean/spree,brchristian/spree,zamiang/spree,zaeznet/spree,Ropeney/spree,edgward/spree,derekluo/spree,KMikhaylovCTG/spree,jimblesm/spree,vmatekole/spree,adaddeo/spree,edgward/spree,sunny2601/spree,JuandGirald/spree,trigrass2/spree,sfcgeorge/spree,robodisco/spree,thogg4/spree,Kagetsuki/spree,jaspreet21anand/spree,Engeltj/spree,njerrywerry/spree,softr8/spree,jimblesm/spree,carlesjove/spree,alvinjean/spree,cutefrank/spree,karlitxo/spree,quentinuys/spree,Lostmyname/spree,robodisco/spree,njerrywerry/spree,delphsoft/spree-store-ballchair,lyzxsc/spree,jasonfb/spree,FadliKun/spree,omarsar/spree,Engeltj/spree,TimurTarasenko/spree,imella/spree,DarkoP/spree,zaeznet/spree,vcavallo/spree,miyazawatomoka/spree,gautamsawhney/spree,gregoryrikson/spree-sample,nooysters/spree,NerdsvilleCEO/spree,azclick/spree,yushine/spree,njerrywerry/spree,agient/agientstorefront,keatonrow/spree,tancnle/spree,Lostmyname/spree,mleglise/spree,moneyspyder/spree,Kagetsuki/spree,piousbox/spree,edgward/spree,JuandGirald/spree,thogg4/spree,reidblomquist/spree,odk211/spree,vinayvinsol/spree,piousbox/spree,shekibobo/spree,sliaquat/spree,locomotivapro/spree,vmatekole/spree,useiichi/spree,caiqinghua/spree,lsirivong/spree,firman/spree,archSeer/spree,useiichi/spree,ayb/spree,alejandromangione/spree,gregoryrikson/spree-sample,NerdsvilleCEO/spree,dandanwei/spree,vinsol/spree,yiqing95/spree,camelmasa/spree,tomash/spree,SadTreeFriends/spree,imella/spree,brchristian/spree,zamiang/spree,volpejoaquin/spree,siddharth28/spree,rbngzlv/spree,rajeevriitm/spree,thogg4/spree,ayb/spree,shaywood2/spree,beni55/spree,volpejoaquin/spree,jeffboulet/spree,caiqinghua/spree,keatonrow/spree,softr8/spree,maybii/spree,lsirivong/spree,moneyspyder/spree,yiqing95/spree,CiscoCloud/spree,hoanghiep90/spree,sunny2601/spree,cutefrank/spree,raow/spree,quentinuys/spree,DynamoMTL/spree,robodisco/spree,Machpowersystems/spree_mach,reinaris/spree,sunny2601/spree,yushine/spree,Hawaiideveloper/shoppingcart,azranel/spree,kewaunited/spree,SadTreeFriends/spree,welitonfreitas/spree,CJMrozek/spree,nooysters/spree,jasonfb/spree,locomotivapro/spree,Ropeney/spree,patdec/spree,beni55/spree,adaddeo/spree,ramkumar-kr/spree,trigrass2/spree,berkes/spree,kewaunited/spree,tesserakt/clean_spree,wolfieorama/spree,alejandromangione/spree,nooysters/spree,pervino/spree,vcavallo/spree,camelmasa/spree,progsri/spree,JuandGirald/spree,odk211/spree,volpejoaquin/spree,shekibobo/spree,abhishekjain16/spree,volpejoaquin/spree,alejandromangione/spree,vulk/spree,groundctrl/spree,odk211/spree,archSeer/spree,jasonfb/spree,jparr/spree,joanblake/spree,moneyspyder/spree,ramkumar-kr/spree,gregoryrikson/spree-sample,quentinuys/spree,dafontaine/spree,SadTreeFriends/spree,jparr/spree,gautamsawhney/spree,firman/spree,vulk/spree,abhishekjain16/spree,mleglise/spree,CiscoCloud/spree,jeffboulet/spree,grzlus/spree,ahmetabdi/spree,reinaris/spree,madetech/spree,reidblomquist/spree,rakibulislam/spree,shekibobo/spree,nooysters/spree,rbngzlv/spree,APohio/spree,AgilTec/spree,priyank-gupta/spree,hifly/spree,abhishekjain16/spree,calvinl/spree,zaeznet/spree,hoanghiep90/spree,delphsoft/spree-store-ballchair,thogg4/spree,welitonfreitas/spree,reidblomquist/spree,yushine/spree,locomotivapro/spree,orenf/spree,vinsol/spree,miyazawatomoka/spree,pulkit21/spree,TimurTarasenko/spree,lsirivong/spree,jasonfb/spree,gautamsawhney/spree,shaywood2/spree,tancnle/spree,vcavallo/spree,dafontaine/spree,CJMrozek/spree,shekibobo/spree,JDutil/spree,lyzxsc/spree,calvinl/spree,moneyspyder/spree,mindvolt/spree,welitonfreitas/spree,kewaunited/spree,priyank-gupta/spree,Lostmyname/spree,adaddeo/spree,AgilTec/spree,kewaunited/spree,archSeer/spree,fahidnasir/spree,fahidnasir/spree,KMikhaylovCTG/spree,azclick/spree,reidblomquist/spree,groundctrl/spree,APohio/spree,madetech/spree,AgilTec/spree,yiqing95/spree,archSeer/spree,mindvolt/spree,beni55/spree,pulkit21/spree,azranel/spree,progsri/spree,madetech/spree,CJMrozek/spree,groundctrl/spree,dandanwei/spree,Kagetsuki/spree,Boomkat/spree,wolfieorama/spree,priyank-gupta/spree,builtbybuffalo/spree,TrialGuides/spree,sliaquat/spree,tesserakt/clean_spree,Engeltj/spree,AgilTec/spree,jspizziri/spree,DarkoP/spree,zaeznet/spree,keatonrow/spree,DarkoP/spree,delphsoft/spree-store-ballchair,orenf/spree,ayb/spree,vinayvinsol/spree,rbngzlv/spree,sunny2601/spree,joanblake/spree,TimurTarasenko/spree,njerrywerry/spree,Kagetsuki/spree,tomash/spree,tancnle/spree,carlesjove/spree,wolfieorama/spree,cutefrank/spree,vinsol/spree,JDutil/spree,vinsol/spree,KMikhaylovCTG/spree,camelmasa/spree,radarseesradar/spree,tancnle/spree,TrialGuides/spree,builtbybuffalo/spree,mindvolt/spree,agient/agientstorefront,robodisco/spree,radarseesradar/spree,orenf/spree,jimblesm/spree,KMikhaylovCTG/spree,jimblesm/spree,tesserakt/clean_spree,progsri/spree,jspizziri/spree,carlesjove/spree,wolfieorama/spree,firman/spree,progsri/spree,rajeevriitm/spree,dandanwei/spree,miyazawatomoka/spree,Machpowersystems/spree_mach,jeffboulet/spree,berkes/spree,CiscoCloud/spree,NerdsvilleCEO/spree,alvinjean/spree,joanblake/spree,agient/agientstorefront,raow/spree,siddharth28/spree,ayb/spree,ahmetabdi/spree,vmatekole/spree,hoanghiep90/spree,radarseesradar/spree,omarsar/spree,JDutil/spree,Boomkat/spree,ramkumar-kr/spree,rakibulislam/spree,hoanghiep90/spree,Lostmyname/spree,pulkit21/spree,azclick/spree,derekluo/spree,DynamoMTL/spree,CJMrozek/spree,tomash/spree,mindvolt/spree,siddharth28/spree,caiqinghua/spree,JuandGirald/spree,pervino/spree,joanblake/spree,sfcgeorge/spree,maybii/spree,carlesjove/spree,jeffboulet/spree,NerdsvilleCEO/spree,karlitxo/spree,Ropeney/spree,dafontaine/spree,alvinjean/spree,hifly/spree,reinaris/spree,rbngzlv/spree,vulk/spree,omarsar/spree,azranel/spree,vinayvinsol/spree,maybii/spree,useiichi/spree,piousbox/spree,radarseesradar/spree,vulk/spree,cutefrank/spree,tomash/spree,ramkumar-kr/spree,TrialGuides/spree,rajeevriitm/spree,groundctrl/spree,piousbox/spree,lyzxsc/spree,camelmasa/spree,CiscoCloud/spree,patdec/spree,APohio/spree,TrialGuides/spree,shaywood2/spree,FadliKun/spree,omarsar/spree,pervino/spree,yiqing95/spree,beni55/spree,FadliKun/spree,calvinl/spree,azranel/spree,brchristian/spree,gautamsawhney/spree,vinayvinsol/spree,builtbybuffalo/spree,derekluo/spree,TimurTarasenko/spree,gregoryrikson/spree-sample,sfcgeorge/spree,derekluo/spree,fahidnasir/spree,jspizziri/spree,priyank-gupta/spree,odk211/spree,quentinuys/spree,dafontaine/spree,jaspreet21anand/spree,yushine/spree,Hawaiideveloper/shoppingcart