Broken link to Coloured Terminal Listings slides

[Oa8choo2]

remark/README.md

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- [Coloured Terminal Listings in remark](http://joshbode.github.com/remark/ansi.html) by [joshbode](https://github.com/joshbode)

http://joshbode.github.com/remark/ansi.html is no longer working.

Subdomains of github.com are deprecated for GitHub Pages. They will not redirect to github.io after April 15, 2021.
The new working link is

https://joshbode.github.io/remark/ansi.html