add migration versioning example to the changelog. [ci skip]
add migration versioning example to the changelog. [ci skip]

Closes #23021.

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