A bit more emphasis on inline code style

I think it would be great for readability if `inline code` were more visible, like the standard GitHub style makes it. And unlike here in Discourse :point_left: this is too subtle just like the current style in Agenda.

I don’t think it should be as highlighted as tags # and people @.

Check out the GitHub style for the exact same markdown as the text above: https://gist.github.com/fcy/b9461859cb460de3ddd0ebc6ae4d0e8d

Thanks for the suggestion, we’ll consider it.