Use more variables in File Name Template

[Andres Jorquera]

Checking the code, I can see that for the File Name we only have a limited amount of variables available. Can you extend this to use more data.

I specifically need the ISBN or the ASIN for the title.

Thanks

obsidian-kindle-plugin/src/rendering/renderer/templateVariables.ts

Line 22 in 99cab6e

 type FileNameTemplateVariables = CommonTemplateVariables & {