Updated the docs.

git-svn-id: svn+ssh://svn.code.sf.net/p/firebird/code/firebird/branches/B2_5_Release@59697 65644016-39b1-43b1-bf79-96bc8fe82c15
Backported fix for CORE-4417 - gbak: cannot commit index ; primary key with german umlaut.

git-svn-id: svn+ssh://svn.code.sf.net/p/firebird/code/firebird/branches/B2_5_Release@59700 65644016-39b1-43b1-bf79-96bc8fe82c15