Adding more default filetypes to DOpus 5 (out of Storage)

[rubicon2026]

Since the File Sniffer comes up on textfiles and AmigaGuides on a default installation,
perhaps it would be a good idea to move these two files out of storage to have a
better out-of-the-box experience.

• ASCII
• AmigaGuide

Maybe there are other filetypes that could be potential candidates, also.