Remove hginit.com (#961)

Removing a non-working hginit.com link.

README.md

 *Useful websites related to web development.*
 
 * [Atlassian Git Tutorials](https://www.atlassian.com/git) - A series of Git tutorials.
-* [Hg Init](http://hginit.com/) - A series of Mercurial tutorials.
 * [Learning Linux](https://linuxjourney.com/) - A website for learning Linux.
 * [Semantic Versioning](https://semver.org/) - A website explaining semantic versioning.
 * [Servers for Hackers](https://serversforhackers.com/) - A newsletter about server management.