Password: Remove reference to non-existing 'password_zxcvbn_min_score' option (#9648)

Author: alecpl

plugins/password/README

@@ -431,7 +431,6 @@
  The library is not distributed with Roundcube (see composer.json-dist).
  Note: Required PHP's memory_limit >= 24M.
 
- Set $config['password_zxcvbn_min_score'] to define minimum acceptable password strength score.
 
  2.2.2. Have I been pwned? (pwned)
  ---------------------------------
@@ -449,6 +448,7 @@
 
  See the driver implementation file for more documentation.
 
+
  3. Driver API
  -------------