[doc] reflect removed models in UPDATE.md.
[doc] reflect removed models in UPDATE.md.

StoreFactory/Payum,fullpipe/Payum,StoreFactory/Payum,emmadery/hello-world,formapro-forks/Payum,aitboudad/Payum,Payum/Payum,ASKozienko/Payum,digisec/Payum,formapro-forks/Payum,staabm/Payum,fullpipe/Payum,digisec/Payum,Payum/Payum,StoreFactory/Payum