minor #16856 [2.8] Added a note about the new requirement iconv (derrabus)
minor #16856 [2.8] Added a note about the new requirement iconv (derrabus)

This PR was merged into the 2.8 branch.

Discussion
----------

[2.8] Added a note about the new requirement iconv

| Q             | A
| ------------- | ---
| Bug fix?      | yes
| New feature?  | no
| BC breaks?    | no
| Deprecations? | no
| Tests pass?   | yes
| Fixed tickets | #16778
| License       | MIT
| Doc PR        | none

When upgrading from 2.7 to 2.8, we need to ensure that `ext-iconv` is present. This PR adds a note about this to the UPGRADE-2.8 file.

Commits
-------

af4f5c5 Added a note about the new requirement iconv.

zerkms/symfony,k0pernikus/symfony,alekitto/symfony,DavidGarciaCat/symfony,c960657/symfony,garak/symfony,garak/symfony,voronkovich/symfony,andreia/symfony,sstok/symfony,apfelbox/symfony,patrick-mcdougle/symfony,ajgarlag/symfony,apetitpa/symfony,andrerom/symfony,sgehrig/symfony,jjanvier/symfony,SaschaDens/symfony,lstrojny/symfony,SofHad/symfony,arjenm/symfony,mpdude/symfony,codeclimate-testing/symfony,lepiaf/symfony,jpauli/symfony,EVODelavega/symfony,dmaicher/symfony,thunderer/symfony,mnapoli/symfony,damienalexandre/symfony,aeoris/symfony,xabbuh/symfony,voronkovich/symfony,jjanvier/symfony,chrisguitarguy/symfony,bburnichon/symfony,gnat42/symfony,mihai-stancu/symfony,localheinz/symfony,damienalexandre/symfony,georaldc/symfony,maidmaid/symfony,zorn-v/symfony,codeclimate-testing/symfony,OndraM/symfony,MisatoTremor/symfony,Einenlum/symfony,Engerim/symfony,GuilhemN/symfony,patrick-mcdougle/symfony,zorn-v/symfony,Ocramius/symfony,danionut90/symfony,jvasseur/symfony,shieldo/symfony,hacfi/symfony,Koc/symfony,EVODelavega/symfony,adamelso/symfony,nasimnabavi/symfony,mnapoli/symfony,zcodes/symfony,Simperfit/symfony,tgalopin/symfony,paradajozsef/symfony,adamelso/symfony,WhiteEagle88/symfony,pyrech/symfony,Triiistan/symfony,jpauli/symfony,mickaelandrieu/symfony,teohhanhui/symfony,Ocramius/symfony,andreia/symfony,1ed/symfony,WhiteEagle88/symfony,oleg-andreyev/symfony,Engerim/symfony,nicolas-grekas/symfony,k0pernikus/symfony,thunderer/symfony,fabpot/symfony,superdav42/symfony,stof/symfony,Simperfit/symfony,SaschaDens/symfony,jderusse/symfony,andrerom/symfony,tucksaun/symfony,Einenlum/symfony,patrick-mcdougle/symfony,webmozart/symfony,weaverryan/symfony,zcodes/symfony,Amo/symfony,alekitto/symfony,HeahDude/symfony,weaverryan/symfony,realityking/symfony,hacfi/symfony,Pierstoval/symfony,joelwurtz/symfony,k0pernikus/symfony,nasimnabavi/symfony,dbu/symfony,jjanvier/symfony,Tobion/symfony,sgehrig/symfony,smatyas/symfony,apfelbox/symfony,dzuelke/symfony,xabbuh/symfony,pix-art/symfony,jjanvier/symfony,alebo/symfony,romaricdrigon/symfony,apfelbox/symfony,dkarvounaris/symfony,danionut90/symfony,ewgRa/symfony,Ener-Getick/symfony,HeahDude/symfony,SaschaDens/symfony,jderusse/symfony,Deamon/symfony,GuilhemN/symfony,e-moe/symfony,jzawadzki/symfony,lemoinem/symfony,jzawadzki/symfony,SaschaDens/symfony,nicolas-grekas/symfony,docteurklein/symfony,mpdude/symfony,tgalopin/symfony,curry684/symfony,superdav42/symfony,thunderer/symfony,DavidGarciaCat/symfony,superdav42/symfony,ajgarlag/symfony,unexge/symfony,lyrixx/symfony,Triiistan/symfony,jpauli/symfony,jameshalsall/symfony,jjanvier/symfony,mickaelandrieu/symfony,joelwurtz/symfony,SofHad/symfony,Slamdunk/symfony,symfony/symfony,jvasseur/symfony,gencer/symfony,ewgRa/symfony,patrick-mcdougle/symfony,Ener-Getick/symfony,okdana/symfony,Tobion/symfony,chalasr/symfony,bburnichon/symfony,romaricdrigon/symfony,gonzalovilaseca/symfony,derrabus/symfony,curry684/symfony,chrisguitarguy/symfony,bburnichon/symfony,pix-art/symfony,pamil/symfony,WouterJ/symfony,stof/symfony,hacfi/symfony,GuilhemN/symfony,natechicago/symfony,joelwurtz/symfony,dbu/symfony,geoffrey-brier/symfony,weaverryan/symfony,Nyholm/symfony,mickaelandrieu/symfony,calm10/Symfony2,oleg-andreyev/symfony,damienalexandre/symfony,apetitpa/symfony,josephdpurcell/symfony,superdav42/symfony,Triiistan/symfony,MatTheCat/symfony,Padam87/symfony,Padam87/symfony,nasimnabavi/symfony,garak/symfony,lstrojny/symfony,hason/symfony,mpdude/symfony,tucksaun/symfony,jean-gui/symfony,yceruto/symfony,chrisguitarguy/symfony,MatTheCat/symfony,Ener-Getick/symfony,believer-ufa/symfony,webmozart/symfony,Strate/symfony,chalasr/symfony,sstok/symfony,gimler/symfony,jpauli/symfony,ogizanagi/symfony,zorn-v/symfony,neemzy/symfony,lemoinem/symfony,michaelperrin/symfony,pix-art/symfony,webmozart/symfony,backbone87/symfony,andrerom/symfony,gnat42/symfony,Koc/symfony,ajgarlag/symfony,Amo/symfony,sroze/symfony,pix-art/symfony,zerkms/symfony,apfelbox/symfony,gimler/symfony,stof/symfony,Simperfit/symfony,dosten/symfony,deguif/symfony,Einenlum/symfony,natechicago/symfony,pyrech/symfony,shieldo/symfony,lemoinem/symfony,maidmaid/symfony,paradajozsef/symfony,geoffrey-brier/symfony,sroze/symfony,garak/symfony,danionut90/symfony,Ocramius/symfony,thunderer/symfony,romainneutron/symfony,Padam87/symfony,dunglas/symfony,zerkms/symfony,pierredup/symfony,digitalkaoz/symfony,dunglas/symfony,d-ph/symfony,teohhanhui/symfony,Slamdunk/symfony,neemzy/symfony,smatyas/symfony,Koc/symfony,phramz/symfony,Simperfit/symfony,Taluu/symfony,Strate/symfony,chrisguitarguy/symfony,Amo/symfony,OndraM/symfony,neemzy/symfony,MatTheCat/symfony,Ener-Getick/symfony,ogizanagi/symfony,georaldc/symfony,Nyholm/symfony,GuilhemN/symfony,adamelso/symfony,shieldo/symfony,ewgRa/symfony,curry684/symfony,Nyholm/symfony,kbond/symfony,mpdude/symfony,Ocramius/symfony,xabbuh/symfony,SofHad/symfony,hhamon/symfony,symfony/symfony,SaschaDens/symfony,realityking/symfony,symfony/symfony,lyrixx/symfony,lyrixx/symfony,josephdpurcell/symfony,michaelperrin/symfony,maidmaid/symfony,yceruto/symfony,oleg-andreyev/symfony,josephdpurcell/symfony,oleg-andreyev/symfony,havvg/symfony,vincentaubert/symfony,natechicago/symfony,derrabus/symfony,Deamon/symfony,vincentaubert/symfony,alebo/symfony,pyrech/symfony,deguif/symfony,gonzalovilaseca/symfony,mickaelandrieu/symfony,OndraM/symfony,csarrazi/symfony,stof/symfony,smatyas/symfony,tgalopin/symfony,natechicago/symfony,mvhirsch/symfony,k0pernikus/symfony,apfelbox/symfony,sroze/symfony,mvhirsch/symfony,localheinz/symfony,dzuelke/symfony,Taluu/symfony,OskarStark/symfony,romainneutron/symfony,dzuelke/symfony,sstok/symfony,hason/symfony,geoffrey-brier/symfony,frankdejonge/symfony,1ed/symfony,tgalopin/symfony,docteurklein/symfony,romainneutron/symfony,hason/symfony,nasimnabavi/symfony,iltar/symfony,michaelperrin/symfony,mvhirsch/symfony,bendavies/symfony,ragboyjr/symfony,pierredup/symfony,Aliance/symfony,symfony/symfony,sgehrig/symfony,andrerom/symfony,k0pernikus/symfony,docteurklein/symfony,pierredup/symfony,natechicago/symfony,dunglas/symfony,jvasseur/symfony,ewgRa/symfony,havvg/symfony,jameshalsall/symfony,believer-ufa/symfony,chrisguitarguy/symfony,klandaika/symfony,mnapoli/symfony,Slamdunk/symfony,pierredup/symfony,frankdejonge/symfony,andreia/symfony,codeclimate-testing/symfony,arjenm/symfony,jpauli/symfony,michaelperrin/symfony,Amo/symfony,webmozart/symfony,believer-ufa/symfony,zcodes/symfony,chalasr/symfony,hhamon/symfony,mweimerskirch/symfony,georaldc/symfony,arjenm/symfony,jakzal/symfony,klandaika/symfony,csarrazi/symfony,lepiaf/symfony,docteurklein/symfony,derrabus/symfony,realityking/symfony,SofHad/symfony,okdana/symfony,iltar/symfony,yceruto/symfony,mweimerskirch/symfony,zorn-v/symfony,zerkms/symfony,ro0NL/symfony,mihai-stancu/symfony,OndraM/symfony,okdana/symfony,Koc/symfony,believer-ufa/symfony,OskarStark/symfony,digitalkaoz/symfony,calm10/Symfony2,e-moe/symfony,MisatoTremor/symfony,vincentaubert/symfony,EVODelavega/symfony,bburnichon/symfony,Deamon/symfony,bburnichon/symfony,realityking/symfony,sroze/symfony,apetitpa/symfony,Tobion/symfony,jean-gui/symfony,joelwurtz/symfony,sstok/symfony,hhamon/symfony,jameshalsall/symfony,WouterJ/symfony,alekitto/symfony,DavidGarciaCat/symfony,gencer/symfony,ro0NL/symfony,alebo/symfony,superdav42/symfony,gonzalovilaseca/symfony,dmaicher/symfony,frankdejonge/symfony,mweimerskirch/symfony,pamil/symfony,ajgarlag/symfony,alebo/symfony,codeclimate-testing/symfony,c960657/symfony,kbond/symfony,mihai-stancu/symfony,OskarStark/symfony,curry684/symfony,Aliance/symfony,smatyas/symfony,jpauli/symfony,hhamon/symfony,Deamon/symfony,mnapoli/symfony,bendavies/symfony,calm10/Symfony2,georaldc/symfony,dzuelke/symfony,unexge/symfony,ro0NL/symfony,bendavies/symfony,calm10/Symfony2,bendavies/symfony,mweimerskirch/symfony,gimler/symfony,pamil/symfony,mihai-stancu/symfony,docteurklein/symfony,maidmaid/symfony,dkarvounaris/symfony,fabpot/symfony,MisatoTremor/symfony,gnat42/symfony,EVODelavega/symfony,zcodes/symfony,aeoris/symfony,Ocramius/symfony,thunderer/symfony,ewgRa/symfony,lemoinem/symfony,localheinz/symfony,pamil/symfony,paradajozsef/symfony,weaverryan/symfony,1ed/symfony,EVODelavega/symfony,dkarvounaris/symfony,mvhirsch/symfony,lstrojny/symfony,fabpot/symfony,jakzal/symfony,unexge/symfony,mvhirsch/symfony,natechicago/symfony,digitalkaoz/symfony,Aliance/symfony,Engerim/symfony,phramz/symfony,HeahDude/symfony,havvg/symfony,Einenlum/symfony,nicolas-grekas/symfony,calm10/Symfony2,ogizanagi/symfony,jzawadzki/symfony,chalasr/symfony,damienalexandre/symfony,Ocramius/symfony,frankdejonge/symfony,lepiaf/symfony,backbone87/symfony,andreia/symfony,ragboyjr/symfony,Pierstoval/symfony,geoffrey-brier/symfony,klandaika/symfony,MisatoTremor/symfony,Amo/symfony,lemoinem/symfony,c960657/symfony,adamelso/symfony,dosten/symfony,Slamdunk/symfony,geoffrey-brier/symfony,jean-gui/symfony,voronkovich/symfony,danionut90/symfony,pyrech/symfony,tucksaun/symfony,webmozart/symfony,ogizanagi/symfony,gencer/symfony,Deamon/symfony,e-moe/symfony,WhiteEagle88/symfony,mihai-stancu/symfony,deguif/symfony,dbu/symfony,jean-gui/symfony,d-ph/symfony,jakzal/symfony,dosten/symfony,unexge/symfony,unexge/symfony,1ed/symfony,havvg/symfony,jameshalsall/symfony,adamelso/symfony,ragboyjr/symfony,Triiistan/symfony,Tobion/symfony,realityking/symfony,d-ph/symfony,superdav42/symfony,teohhanhui/symfony,klandaika/symfony,georaldc/symfony,danionut90/symfony,jderusse/symfony,digitalkaoz/symfony,romaricdrigon/symfony,aeoris/symfony,Padam87/symfony,fabpot/symfony,dosten/symfony,sgehrig/symfony,dbu/symfony,believer-ufa/symfony,Triiistan/symfony,jvasseur/symfony,romainneutron/symfony,kbond/symfony,mweimerskirch/symfony,gonzalovilaseca/symfony,believer-ufa/symfony,shieldo/symfony,dmaicher/symfony,paradajozsef/symfony,realityking/symfony,smatyas/symfony,Pierstoval/symfony,ragboyjr/symfony,geoffrey-brier/symfony,OndraM/symfony,derrabus/symfony,MatTheCat/symfony,SofHad/symfony,iltar/symfony,dmaicher/symfony,backbone87/symfony,OskarStark/symfony,alebo/symfony,dosten/symfony,gimler/symfony,pix-art/symfony,e-moe/symfony,jderusse/symfony,yceruto/symfony,gnat42/symfony,d-ph/symfony,georaldc/symfony,patrick-mcdougle/symfony,localheinz/symfony,sstok/symfony,jameshalsall/symfony,mickaelandrieu/symfony,digitalkaoz/symfony,romainneutron/symfony,dzuelke/symfony,MisatoTremor/symfony,Ener-Getick/symfony,Taluu/symfony,GuilhemN/symfony,phramz/symfony,dkarvounaris/symfony,xabbuh/symfony,c960657/symfony,jakzal/symfony,Strate/symfony,Padam87/symfony,HeahDude/symfony,deguif/symfony,Simperfit/symfony,csarrazi/symfony,Pierstoval/symfony,romaricdrigon/symfony,phramz/symfony,ewgRa/symfony,nicolas-grekas/symfony,dkarvounaris/symfony,Ener-Getick/symfony,havvg/symfony,teohhanhui/symfony,alekitto/symfony,Taluu/symfony,pix-art/symfony,mnapoli/symfony,vincentaubert/symfony,klandaika/symfony,lyrixx/symfony,WouterJ/symfony,danionut90/symfony,Nyholm/symfony,MisatoTremor/symfony,voronkovich/symfony,apetitpa/symfony,kbond/symfony,tucksaun/symfony,iltar/symfony,arjenm/symfony,dbu/symfony,ro0NL/symfony