README: drop Tampermonkey recommendation

I've been using Tampermonkey mostly for it development-related features.
It would seem that nowadays for users of userscripts (as opposed to
developers of userscripts), Violentmonkey is a much better proposition,
with less bloat and less potential privacy-violating tracking.

So drop the Tampermonkey recommendation altogether from README.md.

README.md

@@ -307,7 +307,6 @@ Tampermonkey instructions:
 ### Browser extensions
 
 #### For scripts
-- Recommended: https://www.tampermonkey.net/
 - Big list of different extensions for different browsers available on
   https://greasyfork.org