minor tcpdump.8 inconsistency

minor inconsistency

diff --git a/tcpdump.8 b/tcpdump.8
index ce16951..8c2cf33 100644
--- a/tcpdump.8
+++ b/tcpdump.8
@@ -1257,7 +1257,7 @@ end of this connection.
.Ar window
is the number of bytes of receive buffer space available
at the other end of this connection.
-.Ar urg
+.Ar urgent
indicates there is urgent data in the packet.
.Ar options
are TCP options enclosed in angle brackets e.g.,