Colored the Text on GitHub the Simple Way

I’ve found some colored text in this issue: gohugoio/hugoThemes#682

- Broken themes will be removed around the end of September -

But I remember GFM does not support inline styles. So I googled the topic and found the answer on Stack Overflow.

Looks like the author of this issue just use the syntax of Git diff to colored the text:

- text in red
+ text in green
! text in orange
# text in gray