Do not document pkinit_win2k

This variable was never used in the PKINIT code as it was contributed;
there was only code to read its value.

(cherry picked from commit e161636)

ticket: 8104 (new)
version_fixed: 1.11.6
status: resolved

doc/admin/conf_files/krb5_conf.rst

@@ -977,11 +977,6 @@ PKINIT krb5.conf options
     of the KDC certificate presented.  This option may be specified
     multiple times.
 
-**pkinit_win2k**
-    This flag specifies whether the target realm is assumed to support
-    only the old, pre-RFC version of the protocol.  The default is
-    false.
-
 **pkinit_win2k_require_binding**
     If this flag is set to true, it expects that the target KDC is
     patched to return a reply with a checksum rather than a nonce.