guides, move incomplete example to corresponding option. #21349
guides, move incomplete example to corresponding option. #21349

[ci skip]

This example is dependent on the `:end_at` option and has been removed
from `4-2-stable` (d167b811520a6f800b86c77b805d15505a251bb8)

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