Review examples in gbak documentation for use of filenames only vs protocol

[mrotteveel]

The existing examples in the gbak documentation rely on just using filenames. In same cases it can be better to use explicit protocols and/or host name + filename to ensure the connection goes through the server instead of using embedded (this especially changed on Windows with Firebird 3.0, as Firebird 2.5 (and earlier) would default to XNET, but now defaults to embedded).

Review examples and maybe explicitly mention/document use of protocol instead of only filenames.