`.parse_news()` does not highlight github usernames properly.

[vincentarelbundock]

I did not write this code so will not fix it myself, but noticed that my username is only half highlighted at the top of this document, and that the link does not point to the right username:

http://127.0.0.1:3000/docs/#/NEWS

https://github.com/grantmcdermott/plot2/blob/main/NEWS.md