Docs: note removal of `render :text` option from 5.1 guide [ci skip]
Docs: note removal of `render :text` option from 5.1 guide [ci skip]

This just makes it explicit that the deprecated :text option is
completely removed in Rails 5.1

esparta/rails,vipulnsward/rails,yhirano55/rails,esparta/rails,georgeclaghorn/rails,Edouard-chin/rails,rails/rails,schuetzm/rails,shioyama/rails,repinel/rails,jeremy/rails,tgxworld/rails,tgxworld/rails,tjschuck/rails,vipulnsward/rails,yalab/rails,starknx/rails,Erol/rails,joonyou/rails,kmcphillips/rails,yhirano55/rails,yhirano55/rails,schuetzm/rails,betesh/rails,BlakeWilliams/rails,yawboakye/rails,georgeclaghorn/rails,kddeisz/rails,Stellenticket/rails,MSP-Greg/rails,betesh/rails,georgeclaghorn/rails,yahonda/rails,yawboakye/rails,yhirano55/rails,kddeisz/rails,starknx/rails,mechanicles/rails,Stellenticket/rails,yawboakye/rails,tjschuck/rails,notapatch/rails,tjschuck/rails,bogdanvlviv/rails,joonyou/rails,tgxworld/rails,eileencodes/rails,esparta/rails,eileencodes/rails,Stellenticket/rails,eileencodes/rails,jeremy/rails,starknx/rails,jeremy/rails,rafaelfranca/omg-rails,repinel/rails,shioyama/rails,notapatch/rails,shioyama/rails,BlakeWilliams/rails,lcreid/rails,MSP-Greg/rails,eileencodes/rails,BlakeWilliams/rails,yahonda/rails,MSP-Greg/rails,palkan/rails,notapatch/rails,BlakeWilliams/rails,Vasfed/rails,Envek/rails,tgxworld/rails,palkan/rails,iainbeeston/rails,joonyou/rails,fabianoleittes/rails,joonyou/rails,Envek/rails,Edouard-chin/rails,shioyama/rails,yalab/rails,kddeisz/rails,iainbeeston/rails,Erol/rails,palkan/rails,rafaelfranca/omg-rails,gauravtiwari/rails,yahonda/rails,betesh/rails,gauravtiwari/rails,prathamesh-sonpatki/rails,iainbeeston/rails,jeremy/rails,Edouard-chin/rails,EmmaB/rails-1,Erol/rails,prathamesh-sonpatki/rails,Vasfed/rails,lcreid/rails,yawboakye/rails,bogdanvlviv/rails,lcreid/rails,schuetzm/rails,Erol/rails,rafaelfranca/omg-rails,georgeclaghorn/rails,yalab/rails,iainbeeston/rails,yahonda/rails,vipulnsward/rails,MSP-Greg/rails,prathamesh-sonpatki/rails,rails/rails,esparta/rails,Edouard-chin/rails,Envek/rails,palkan/rails,prathamesh-sonpatki/rails,fabianoleittes/rails,fabianoleittes/rails,bogdanvlviv/rails,mechanicles/rails,tjschuck/rails,kddeisz/rails,bogdanvlviv/rails,rails/rails,fabianoleittes/rails,mechanicles/rails,Vasfed/rails,repinel/rails,gauravtiwari/rails,betesh/rails,Envek/rails,rails/rails,kmcphillips/rails,kmcphillips/rails,yalab/rails,notapatch/rails,schuetzm/rails,EmmaB/rails-1,vipulnsward/rails,Vasfed/rails,mechanicles/rails,kmcphillips/rails,lcreid/rails,repinel/rails,EmmaB/rails-1,Stellenticket/rails