[1.6.x] Fixed documentation of make_password kwargs.

        to be an unusable password, resulting in this method returning

        ``False`` for such a password.

.. function:: make_password(password[, salt, hashers])

.. function:: make_password(password, salt=None, hasher='default')

    Creates a hashed password in the format used by this application. It takes

    one mandatory argument: the password in plain-text. Optionally, you can