Add issue templates

[MichaelHinrichs]

Create Issue templates for file misdetection and requests for new file types.

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[reyammer]

Did some tweaks and merged. Thank you!

[reyammer]

Interesting... one of the "fix" was to change "about" => "description" metadata, as it seemed the correct one. See screenshot. But then I got errors, "about" seems to be the correct metadata key. Anyways, fixed now.