Add docs about _scopes option on enum. [ci skip]
Add docs about _scopes option on enum. [ci skip]

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