Update Rails 5 release notes [ci skip]
Update Rails 5 release notes [ci skip]

- Removed entry for # Template Collection from release notes.
- Remove duplicate entry for caching Action mailer views.
- Remove duplicate entry for left_outer_joins.

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