Add support for `.qmd` files

[dropsplash]

add qmd files (quarto) https://quarto.org/

[chamburr]

Kindly read the contributing section in readme on how to add support for a new file extension. You will also need to update all instances of code and text where markdown is mentioned, and add a test file in GlanceTests following the same format.

[dropsplash]

Thanks for the information, I try to complete the process. It should not be that difficult to account files with qmd extension as a markdown file (such as Rmd). But to be honest, my knowledge is quite limited in swift coding and I'm not sure that I'm able to go further. I hope it helps and will be very grateful if you could consider adding such features. Thanks so much for your work on this software. Kind regards

[chamburr]

Thanks!