Allow configuration of text size

[MilesMcBain]

Hey there

Thanks for the very cool extension!

I see multiple issues about font size (edit: e.g. #17, #22). I'm no TS/JS developer, but here is a sketch of a way that could be done that would also scale easily to other configurable style elements, e.g. font family and weight.

Thanks!

[FilipAndersson245]

@mattbierner what is needed to close this PR? it would be very nice to be able to configure the font size.

[emlautarom1]

Also asking if we could merge this one out!

[nagoli]

Waiting for the feature to be accepted, you can simply change the text size in the css of the extension : ~/.vscode/extensions/bierner.docs-view-0.0.11/media/main.css