Fixed typo in migrations guide
Fixed typo in migrations guide

Product model name was pluralized in example in migrations guide.
[ci skip]

eileencodes/rails,repinel/rails,brchristian/rails,brchristian/rails,shioyama/rails,elfassy/rails,betesh/rails,vassilevsky/rails,palkan/rails,baerjam/rails,assain/rails,yhirano55/rails,odedniv/rails,kddeisz/rails,gcourtemanche/rails,kaspth/rails,ttanimichi/rails,kenta-s/rails,EmmaB/rails-1,felipecvo/rails,utilum/rails,Edouard-chin/rails,hanystudy/rails,kenta-s/rails,ngpestelos/rails,kddeisz/rails,stefanmb/rails,printercu/rails,odedniv/rails,illacceptanything/illacceptanything,utilum/rails,aditya-kapoor/rails,rossta/rails,jeremy/rails,sergey-alekseev/rails,ttanimichi/rails,mijoharas/rails,assain/rails,fabianoleittes/rails,yhirano55/rails,repinel/rails,joonyou/rails,betesh/rails,bradleypriest/rails,prathamesh-sonpatki/rails,sealocal/rails,mathieujobin/reduced-rails-for-travis,pschambacher/rails,mtsmfm/railstest,Erol/rails,tijwelch/rails,mohitnatoo/rails,deraru/rails,rossta/rails,mechanicles/rails,lcreid/rails,arunagw/rails,yasslab/railsguides.jp,maicher/rails,MSP-Greg/rails,rafaelfranca/omg-rails,MSP-Greg/rails,riseshia/railsguides.kr,tjschuck/rails,Stellenticket/rails,deraru/rails,xlymian/rails,stefanmb/rails,baerjam/rails,vipulnsward/rails,untidy-hair/rails,vipulnsward/rails,rails/rails,schuetzm/rails,riseshia/railsguides.kr,prathamesh-sonpatki/rails,alecspopa/rails,aditya-kapoor/rails,jeremy/rails,aditya-kapoor/rails,Edouard-chin/rails,yawboakye/rails,kmcphillips/rails,esparta/rails,yalab/rails,yahonda/rails,betesh/rails,MichaelSp/rails,gcourtemanche/rails,ngpestelos/rails,felipecvo/rails,tgxworld/rails,pvalena/rails,xlymian/rails,Vasfed/rails,utilum/rails,travisofthenorth/rails,gauravtiwari/rails,tjschuck/rails,illacceptanything/illacceptanything,arunagw/rails,Envek/rails,rails/rails,rafaelfranca/omg-rails,koic/rails,rossta/rails,rails/rails,88rabbit/newRails,schuetzm/rails,printercu/rails,arjes/rails,printercu/rails,yahonda/rails,mohitnatoo/rails,gfvcastro/rails,pvalena/rails,ngpestelos/rails,kddeisz/rails,hanystudy/rails,bradleypriest/rails,fabianoleittes/rails,lucasmazza/rails,kmayer/rails,Vasfed/rails,tgxworld/rails,bogdanvlviv/rails,rbhitchcock/rails,matrinox/rails,kirs/rails-1,iainbeeston/rails,palkan/rails,illacceptanything/illacceptanything,Erol/rails,assain/rails,kenta-s/rails,mijoharas/rails,Edouard-chin/rails,baerjam/rails,printercu/rails,MichaelSp/rails,xlymian/rails,joonyou/rails,georgeclaghorn/rails,tijwelch/rails,elfassy/rails,elfassy/rails,Vasfed/rails,shioyama/rails,Spin42/rails,gavingmiller/rails,gavingmiller/rails,sergey-alekseev/rails,flanger001/rails,kachick/rails,kmcphillips/rails,betesh/rails,pschambacher/rails,rbhitchcock/rails,untidy-hair/rails,schuetzm/rails,kamipo/rails,mathieujobin/reduced-rails-for-travis,stefanmb/rails,Stellenticket/rails,yawboakye/rails,brchristian/rails,bolek/rails,gfvcastro/rails,illacceptanything/illacceptanything,alecspopa/rails,georgeclaghorn/rails,flanger001/rails,shioyama/rails,aditya-kapoor/rails,arunagw/rails,samphilipd/rails,lucasmazza/rails,voray/rails,gauravtiwari/rails,untidy-hair/rails,Erol/rails,voray/rails,coreyward/rails,yahonda/rails,BlakeWilliams/rails,shioyama/rails,travisofthenorth/rails,Envek/rails,EmmaB/rails-1,vipulnsward/rails,esparta/rails,yalab/rails,georgeclaghorn/rails,Erol/rails,yasslab/railsguides.jp,coreyward/rails,lcreid/rails,rafaelfranca/omg-rails,notapatch/rails,felipecvo/rails,yawboakye/rails,iainbeeston/rails,marklocklear/rails,bradleypriest/rails,BlakeWilliams/rails,gcourtemanche/rails,ttanimichi/rails,illacceptanything/illacceptanything,BlakeWilliams/rails,iainbeeston/rails,repinel/rails,odedniv/rails,tgxworld/rails,illacceptanything/illacceptanything,richseviora/rails,lucasmazza/rails,illacceptanything/illacceptanything,amoody2108/TechForJustice,palkan/rails,arjes/rails,mohitnatoo/rails,mechanicles/rails,richseviora/rails,mohitnatoo/rails,lcreid/rails,kmayer/rails,EmmaB/rails-1,Spin42/rails,joonyou/rails,tgxworld/rails,mathieujobin/reduced-rails-for-travis,amoody2108/TechForJustice,gfvcastro/rails,Spin42/rails,prathamesh-sonpatki/rails,bogdanvlviv/rails,illacceptanything/illacceptanything,marklocklear/rails,mtsmfm/rails,yasslab/railsguides.jp,baerjam/rails,Vasfed/rails,MichaelSp/rails,notapatch/rails,kachick/rails,utilum/rails,koic/rails,sealocal/rails,vassilevsky/rails,kmcphillips/rails,flanger001/rails,illacceptanything/illacceptanything,pvalena/rails,tjschuck/rails,Stellenticket/rails,kamipo/rails,mtsmfm/rails,illacceptanything/illacceptanything,illacceptanything/illacceptanything,illacceptanything/illacceptanything,deraru/rails,illacceptanything/illacceptanything,mechanicles/rails,voray/rails,travisofthenorth/rails,mtsmfm/railstest,samphilipd/rails,amoody2108/TechForJustice,eileencodes/rails,notapatch/rails,gauravtiwari/rails,starknx/rails,mechanicles/rails,deraru/rails,88rabbit/newRails,MSP-Greg/rails,arunagw/rails,Sen-Zhang/rails,yhirano55/rails,vipulnsward/rails,sealocal/rails,BlakeWilliams/rails,kirs/rails-1,bogdanvlviv/rails,Sen-Zhang/rails,Envek/rails,notapatch/rails,yalab/rails,yawboakye/rails,gfvcastro/rail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