[doc] add working-with-sensitive-information.md to index.md list.
[doc] add working-with-sensitive-information.md to index.md list.
fullpipe/Payum,Payum/Payum,formapro-forks/Payum,ASKozienko/Payum,Payum/Payum,StoreFactory/Payum,StoreFactory/Payum,fullpipe/Payum,staabm/Payum,StoreFactory/Payum,digisec/Payum,aitboudad/Payum,digisec/Payum,formapro-forks/Payum