Label the OpenSSH section, then add a small explanation for the existence

of the non-typo "csshd" service.

Prodded by:	markm
Reviewed by:	markm, dwhite, rwatson

etc/pam.conf

@@ -75,6 +75,7 @@ ftp	auth	required	pam_unix.so			try_first_pass
 ftp	account	required	pam_unix.so
 #ftp	session	required	pam_krb5.so
 
+# OpenSSH
 #sshd	auth	sufficient	pam_krb5.so
 sshd	auth	required	pam_unix.so			try_first_pass
 #sshd	account	required	pam_krb5.so
@@ -82,6 +83,7 @@ sshd	account	required	pam_unix.so
 sshd	password required	pam_permit.so
 #sshd	session	required	pam_krb5.so
 sshd	session	required	pam_permit.so
+# "csshd" is for challenge-based authentication with sshd (TIS auth, etc.)
 csshd	auth	required	pam_skey.so
 
 # Don't break startx