Extras assets, support multiple text files for the readme

[bengarrett]

Currently a single README and the FILE_ID.DIZ can be displayed.

There is a need to support multiple files at once, for example:

https://defacto2.net/f/b52f65a (CB30REG.ZIP) has the following content.

• FILE_ID.DIZ
• MCC.NFO
• MCC.LST

Maybe we can have [UUID].TXT then [UUID].TXT1 [UUID].TXT2 etc.
If no .TXT1 is found, abort the reading range loop?

Another naming syntax could be [UUID].1.TXT, [UUID].2.TXT.