refine doc

docs/authenticator.md

@@ -28,7 +28,7 @@ CREATE TABLE users (
 );
 ```
 
-Note that trojan will only read/write the `password`, `quota`, `download`, and `upload` fields. Other fields exist for management convenience. The passwords stored in the table have to be hashed by SHA224 for efficiency and security reasons. You can use [trojan-manager](https://github.com/trojan-gfw/trojan-manager) (which stores passwords as `SHA224(username:password)` so that clients have to prepend `username:` to the passwords in their config files) to manage users in the database.
+Note that trojan will only read/write the `password`, `quota`, `download`, and `upload` fields. Other fields exist for management convenience. The passwords stored in the table have to be hashed by SHA224 for efficiency and security reasons.
 
 Upon receiving a Trojan Request, **if the server fails to match the password with any passwords set in the config file**, it will query the database for the user. If it succeeds, trojan will check whether `download + upload < quota`; if so, the connection is granted. **A negative `quota` value means infinite quota.** After a connection is closed, trojan will increment `download` and `upload` fields of that user by the amount of data the user has used.