minor #18442 [HttpFoundation] Improve phpdoc (mnapoli)
minor #18442 [HttpFoundation] Improve phpdoc (mnapoli)

This PR was submitted for the master branch but it was merged into the 2.3 branch instead (closes #18442).

Discussion
----------

[HttpFoundation] Improve phpdoc

| Q             | A
| ------------- | ---
| Branch?       | master?
| Bug fix?      | no
| New feature?  | no
| BC breaks?    | no
| Deprecations? | no
| Tests pass?   | yes
| Fixed tickets | -
| License       | MIT
| Doc PR        | -

Improve the phpdoc for the `$default` parameter of the `get()` method. It wasn't clear when the default value would be used (whether the key would not exist or the value was `null` or nullish).

The comment is now in sync with `Symfony\Component\HttpFoundation\ParameterBag::get()`.

Commits
-------

6bfbb2e [HttpFoundation] Improve phpdoc

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