Update app.ini.sample (#7817)

small grammar fix

Author: proailurus

custom/conf/app.ini.sample

@@ -724,7 +724,7 @@ ACCESS_TOKEN_EXPIRATION_TIME=3600
 REFRESH_TOKEN_EXPIRATION_TIME=730
 ; Check if refresh token got already used
 INVALIDATE_REFRESH_TOKENS=false
-; OAuth2 authentication secret for access and refresh tokens, change this a unique string.
+; OAuth2 authentication secret for access and refresh tokens, change this to a unique string.
 JWT_SECRET=Bk0yK7Y9g_p56v86KaHqjSbxvNvu3SbKoOdOt2ZcXvU
 
 [i18n]