update Pastel Paws theme entry to match new url

I did my homework
added Dark Eight theme

A dark theme matching Windows 8's chrome

Note: We know forks exists, however we obtained ownership of the original theme repository and we plan to maintain it.
[Pastel Paws]: Fix previous_names keywords
Merge pull request #3622 from Ociidii-Works/master

Updated url for Pastel Paws, added Dark Eight theme