LDAP username placeholder

Description

I would like to describe username format on the login page in the form of a placeholder so it will be easier for first-time users to sign in.

Proposal

Add a property to the LDAP configuration documentation:

  # The placeholder that should be shown in the username field on the login pace
  #
  #   Ex. username@domain.corp
  #
  username_placeholder: ''

Links / references

None.

Documentation blurb

See proposal.