Update wording in slapd.conf.5 to match admin guide

fix "require" inheritance and handling of "none" (ITS#4574)
Add access control note to authz-regexp discussion
ITS#4613 note that lastmod also controls entryCSN and entryUUID

+       Fixed libldap disable DH key exchange with DH params (ITS#4354)
+       Fixed libldap_r pool destroy hang (ITS#4349)
+       Fixed slapd(8) solaris select(2) issue (ITS#4357)

clarify that the names of the configure statements are case-insensitive, despite style considerations lead to use uppercase for some and lowercase for others

with ldapi:// sessions.