I have founded a couple more problems in "Add JSF capabilities" dialog
#1 When we click browse button it's show files select menus relativity to folder where eclipse has been installed. It's should show files select menu relative to project for which dialog has been called or eclipse workspace. You can try for example create new file using CNTRL+N menu and see how works file select dialog in eclipse.
#2 To add jsf capabilities i should select existing web.xml. I have created simple java project, then created folder web, in this folder created web.xml and select my web.xml in this dialog. After dialog has finish the work in project was added one more web.xml descriptor.Why?