Audiobook: Allow linking to PDF supplementary materials

[ZLoth 4]

There are some audiobooks, most notably the "Great Courses" which include a supplementary PDF that is available as part of the book. Emby should have a way to link or pick up a PDF that is in the same folder as an audiobook. 

[Luke 42078]

HI, yes it's an interesting idea that has come up before and is always possible for future updates. Thanks.

[ebr 16184]

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