add section in README for configuring paperclip on Ubuntu
add section in README for configuring paperclip on Ubuntu

danilke/magazin,tiveor/ror_ecommerce,drhenner/elzzad,paulhd/Gutscheine,kewaunited/ror_ecommerce,arthursllaw/ror_ecommerce,mycee0001/ror_ecommerce-master,drhenner/ror_ecommerce,nathanael2020/rore,arthursllaw/ror_ecommerce,mycee0001/ror_ecommerce-master,drhenner/founderslogic,danilke/magazin,WebwinkeleninNL/wwi,drhenner/angel_deck,frenkly/artychoke,ragnarisxx/ktis,jparbros/magnolia_cream,tiveor/ror_ecommerce,danilke/magazin,drhenner/angel_deck,kewaunited/ror_ecommerce,gustavoguichard/qrshirts,nathanael2020/rore,danilke/magazin,lxiaodao/ror_ecommerce,WebwinkeleninNL/wwi,ajmalafif/pasar-rore,zjr/o-junk-ecomm-site,gustavoguichard/qrshirts,mycee0001/ror_ecommerce-master,zjr/o-junk-ecomm-site,tjblonsk/ecommerce_prototype,frenkly/artychoke,ragnarisxx/ktis,zjr/o-junk-ecomm-site,zjr/o-junk-ecomm-site,drhenner/angel_deck,rommelk/Ecommerce,sunilvrao/vaultme-web,danielstanojevic/ror_ecommerce,drhenner/elzzad,lxiaodao/ror_ecommerce,jparbros/magnolia_cream,danielstanojevic/ror_ecommerce,drhenner/founderslogic,drhenner/angel_deck,rommelk/Ecommerce,lxiaodao/ror_ecommerce,drhenner/ror_ecommerce,sunilvrao/vaultme-web,epireve/Kffy,paulhd/Gutscheine,tiveor/ror_ecommerce,epireve/Kffy,rommelk/Ecommerce,ajmalafif/pasar-rore,danielstanojevic/ror_ecommerce,tjblonsk/ecommerce_prototype,kewaunited/ror_ecommerce,apexkid/sally,arthursllaw/ror_ecommerce,paulhd/Gutscheine,ragnarisxx/ktis,drhenner/ror_ecommerce,frenkly/artychoke,apexkid/sally