Added Cs.rin.ru as a custom site.

[QuestionableNinja]

Short of someone much better with website querying than me (not difficult to do), I figured out I could get the extension to search cs.rin.ru's forums using this search URL:
https://cs.rin.ru/forum/search.php?keywords=

I hope this helps those like myself who like to use Rin.

As a bonus for reading to the end, here's an icon I found for the site:
https://www.userlogos.org/files/logos/jumpordie/csrinru_03.png

[iMAboud]

cs.rin requires sign-up to search and use, that's why it's not included in the extension, but thanks for sharing