Clarify documentation on intent of application

[Fmstrat]

Since there is nothing in the README that states otherwise, I and I'm seeing others (example: #5) are easily confused by the purpose of this connector, thinking that it synchronizes users via LDAP.

A version of the statement from the Wiki should be included at the very top of this README:

This service does not synchronize users between your LDAP server and Vaultwarden. Instead, LDAP integration is performed by querying your LDAP server and inviting users to your Vaultwarden instance.

[ViViDboarder]

Sure, I do state this as the second line in the eadme:

After configuring, run vaultwarden_ldap and it will invite any users it finds in LDAP to your vaultwarden instance.

However, I do see that is ambiguous as it doesn't explicitly state that it is all it does. I'll make some edits.

[Fmstrat]

Thanks!