Update UPGRADE.md to point to the doctrine 2.4 changelog.
Update UPGRADE.md to point to the doctrine 2.4 changelog.

xabbuh/shopware,FiveDigital/shopware,mreiss/shopware,wesolowski/shopware,k10r/shopware,kayyyy/shopware-4,cyberid41/shopware,oktupol/shopware,mreiss/shopware,buddhaCode/shopware,ahoehne/shopware-4,oktupol/shopware,wesolowski/shopware,s-haase/shopware,jenalgit/shopware,jenalgit/shopware,cyberid41/shopware,Zwilla/shopware,buddhaCode/shopware,Sunchairs/shopware,philippmahlow/shopware,DerRidda/shopware,egoistIT/shopware,buddhaCode/shopware,VIISON/shopware-4,zeroseven/shopware,ShopwareHackathon/dompdf,ShopwareHackathon/shopware_search_optimization,bcremer/shopware,dNovo/shopware,jhit/shopware,wolv-dev/shopware,buddhaCode/shopware,xabbuh/shopware,xabbuh/shopware,dNovo/shopware,fegoulart/shopware,OliverZachau/shopware-4,zeroseven/shopware,simkli/shopware,kayyyy/shopware-4,fegoulart/shopware,ShopwareHackathon/shopware_search_optimization,ShopwareHackathon/shopware_media,ShopwareHackathon/scale-commerce-ongr-bundle,arvatis/shopware,arvatis/shopware,bcremer/shopware,Pttde/shopware,patricktreiber/shopware_test,giginos/shopware,patricktreiber/shopware_test,Pttde/shopware,cyberid41/shopware,SvenHerrmann/shopware,Sunchairs/shopware,cyberid41/shopware,philippmahlow/shopware,Zwilla/shopware,FiveDigital/shopware,xabbuh/shopware,JonidBendo/shopware,k10r/shopware,cyberid41/shopware,b3nl/shopware,ShopwareHackathon/scale-commerce-ongr-bundle,zeroseven/shopware,ShopwareHackathon/scale-commerce-ongr-bundle,SvenHerrmann/shopware,NetInventors/shopware,kayyyy/shopware-4,egoistIT/shopware,t2oh4e/shopware,SvenHerrmann/shopware,JonidBendo/shopware,simkli/shopware,b3nl/shopware,simkli/shopware,OliverZachau/shopware-4,ShopwareHackathon/dompdf,NetInventors/shopware,DerRidda/shopware,dnoegel/shopware-aop,JonidBendo/shopware,oktupol/shopware,Pttde/shopware,Zwilla/shopware,FiveDigital/shopware,jenalgit/shopware,giginos/shopware,dNovo/shopware,Sunchairs/shopware,VIISON/shopware-4,zeroseven/shopware,wolv-dev/shopware,jenalgit/shopware,ShopwareHackathon/shopware_search_optimization,VIISON/shopware-4,fegoulart/shopware,SvenHerrmann/shopware,ShopwareHackathon/scale-commerce-ongr-bundle,NetInventors/shopware,ShopwareHackathon/shopware-ajax-variant,ShopwareHackathon/shopware_search_optimization,t2oh4e/shopware,patricktreiber/shopware_test,SvenHerrmann/shopware,Pttde/shopware,s-haase/shopware,philippmahlow/shopware,ahoehne/shopware-4,ShopwareHackathon/shopware-ajax-variant,oktupol/shopware,dnoegel/shopware-aop,dnoegel/shopware-aop,buddhaCode/shopware,b3nl/shopware,dnoegel/shopware-aop,ShopwareHackathon/dompdf,jhit/shopware,ShopwareHackathon/shopware-ajax-variant,ShopwareHackathon/shopware-ajax-variant,simkli/shopware,jhit/shopware,Sunchairs/shopware,mreiss/shopware,t2oh4e/shopware,ahoehne/shopware-4,k10r/shopware,JonidBendo/shopware,kayyyy/shopware-4,k10r/shopware,wesolowski/shopware,ShopwareHackathon/shopware-ajax-variant,ahoehne/shopware-4,FiveDigital/shopware,jochenmanz/shopware,philippmahlow/shopware,t2oh4e/shopware,FiveDigital/shopware,k10r/shopware,richardbruse/shopware,dnoegel/shopware-aop,philippmahlow/shopware,egoistIT/shopware,ShopwareHackathon/scale-commerce-ongr-bundle,DerRidda/shopware,b3nl/shopware,s-haase/shopware,bcremer/shopware,arvatis/shopware,ShopwareHackathon/dompdf,giginos/shopware,fegoulart/shopware,egoistIT/shopware,jhit/shopware,richardbruse/shopware,OliverZachau/shopware-4,wesolowski/shopware,bcremer/shopware,Pttde/shopware,JonidBendo/shopware,richardbruse/shopware,fegoulart/shopware,Zwilla/shopware,jochenmanz/shopware,dNovo/shopware,VIISON/shopware-4,ShopwareHackathon/shopware_media,DerRidda/shopware,NetInventors/shopware,kayyyy/shopware-4,OliverZachau/shopware-4,egoistIT/shopware,wolv-dev/shopware,Zwilla/shopware,xabbuh/shopware,jochenmanz/shopware,mreiss/shopware,patricktreiber/shopware_test,jenalgit/shopware,t2oh4e/shopware,richardbruse/shopware,jhit/shopware,s-haase/shopware,jochenmanz/shopware,ShopwareHackathon/shopware_media,giginos/shopware,patricktreiber/shopware_test,wolv-dev/shopware,ShopwareHackathon/shopware_media,dNovo/shopware,bcremer/shopware,wolv-dev/shopware,simkli/shopware,s-haase/shopware,zeroseven/shopware,ShopwareHackathon/dompdf,richardbruse/shopware,mreiss/shopware,arvatis/shopware,ShopwareHackathon/shopware_media,DerRidda/shopware,arvatis/shopware,jochenmanz/shopware,giginos/shopware,ShopwareHackathon/shopware_search_optimization,wesolowski/shopware,VIISON/shopware-4,Sunchairs/shopware,NetInventors/shopware,oktupol/shopware