added FAQ about file locking
added FAQ about file locking

svn path=/trunk/kdenetwork/doc/kmail/; revision=69518

lefou/kdepim-noakonadi,lefou/kdepim-noakonadi,lefou/kdepim-noakonadi,lefou/kdepim-noakonadi,lefou/kdepim-noakonadi,lefou/kdepim-noakonadi