docs: add references about why we use crypto.timingSafeEqual (#525)

Author: gr2m

src/verify/index.ts

@@ -28,5 +28,8 @@ export function verify(
     return false;
   }
 
+  // constant time comparison to prevent timing attachs
+  // https://stackoverflow.com/a/31096242/206879
+  // https://en.wikipedia.org/wiki/Timing_attack
   return timingSafeEqual(signatureBuffer, verificationBuffer);
 }