dhcpd: typo in dhcpd.conf.5 manpage

There is a small typo in the dhcpd.conf.5 manpage, where prefix6 is written as prefixy6. This parameter doesn't seem to be mentioned anywhere else, so I assume it to be a mistake.

Patch against latest master below.

diff --git a/server/dhcpd.conf.5 b/server/dhcpd.conf.5
index d3b2ae8..9cc6b74 100644
--- a/server/dhcpd.conf.5
+++ b/server/dhcpd.conf.5
@@ -322,7 +322,7 @@ Currently it is only allowed within a \fBsubnet6\fR declaration, and
 may not be included directly in a shared network declaration.
 In addition to the \fBrange6\fR statement it allows the \fBprefix6\fR
 statement to be included.  You may include \fBrange6\fR statements
-for both NA and TA and \fBprefixy6\fR statements in a single
+for both NA and TA and \fBprefix6\fR statements in a single
 \fBpool6\fR statement.
 .SH DYNAMIC ADDRESS ALLOCATION
 Address allocation is actually only done when a client is in the INIT