Looks like a typo of "vary" instead of "wary", and "aware" sounds better.
// ***********************************
define('ENABLE_REGISTRATION', false);
- // Allow users to register themselves. Please be vary that allowing
+ // Allow users to register themselves. Please be aware that allowing
// random people to access your tt-rss installation is a security risk
// and potentially might lead to data loss or server exploit. Disabled
// by default.