AUTH_LDAP_USE_TLS is named ambiguously

[a-gerhard]

(Removing issue template as nothing here really fits into that template anyways)

I recently opened Pull Request #1988

One thing that the docs couldn't really fix is the ambiguous naming of the AUTH_LDAP_USE_TLS setting. LDAP has two ways of doing TLS: Either open an unencrypted TCP connection (default Port 389) and protect it by negotiating STARTTLS, or directly connect through TLS (default port 636). The setting's name doesn't provide any hint on what is actually used – and that made it quite hard to debug, especially without any documentation around it.

I would suggest to rename the setting to AUTH_LDAP_USE_STARTTLS for clarity.