Fixed validation issue and titles in Migrations guide [ci skip]
Fixed validation issue and titles in Migrations guide [ci skip]

Changed the title of the 3.5 chapter from "Using the change Method" to
"When to Use the change Method" since the chapter tells the migration
definitions supported by the change method. This fix the duplicate ID in the
document.

I've also changed some of the titles to respect the Guides guidelines.

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