Remove non-existent password_strength setting from the reference

Author: stof

Diff for: reference/configuration/framework.rst

@@ -2840,14 +2840,6 @@ metadata of the class. You can define an array of strings with the names of
 several methods. In that case, all of them will be called in that order to load
 the metadata.
 
-.. _reference-validation-password-strength:
-
-password_strength
-.................
-
-The :doc:`PasswordStrength </reference/constraints/PasswordStrength>`
-constraint verifies the submitted string entropy is matching the minimum entropy score.
-
 .. _reference-validation-email_validation_mode:
 
 email_validation_mode