Preview more text-based files

[rs1-es]

Note: Please write your issue only in english

Is your feature request related to a problem? Please describe.
Some plain-text files cannot be previewed on the app, but can be previewed on the web (Markdown files, for example)

Describe the solution you'd like
Allow to preview at least the same files as the web version of kDrive.

Describe alternatives you've considered

Additional context

[Lnamw]

Hello,
Thank you for bringing this issue to our attention.
We’ll have a look at it.

[gabethehuman]

+1, would be great to be able to preview markdown files.