Add warning for fake site

Someone has registered protontricks [dot] com and published a fake site on
it full of nonsense.

Proton-GE has dealt with a similar problem and added a prominent warning
on the project README. Do the same here.

Author: Matoking

README.md

@@ -1,3 +1,6 @@
+> [!CAUTION]
+> **`hxxps[://]protontricks[.]com` IS A FAKE SITE** and not affiliated with any of the Protontricks developers. https://github.com/Matoking/protontricks is the only official page for Protontricks.
+
 Protontricks
 ============