manuals: Misc syntax fixes

These were reported by `mandoc -T lint ...` as errors.

Signed-off-by:	Graham Percival <gperciva@tarsnap.com>
Reviewed by:	mhorne
MFC after:	3 days
Sponsored by:	Tarsnap Backup Inc.
Pull Request:	https://github.com/freebsd/freebsd-src/pull/1453

(cherry picked from commit 8b92fa1ceb95bbe80b473fc35d4276146201e802)

lib/librss/librss.3

@@ -109,8 +109,8 @@ socket.
 The
 .Fn rss_sock_set_recvrss
 function enables or disables receiving RSS related information
-as socket options in.
-.2 recvmsg
+as socket options in
+.Xr recvmsg 2
 calls.
 .Pp
 When enabled, UDP datagrams will have a message with the

share/man/man4/bpf.4

@@ -665,7 +665,7 @@ Set the VLAN PCP bits to the supplied value.
 now supports several standard
 .Xr ioctl 2 Ns 's
 which allow the user to do async and/or non-blocking I/O to an open
-.I bpf
+.Em bpf
 file descriptor.
 .Bl -tag -width SIOCGIFADDR
 .It Dv FIONREAD

share/man/man7/orders.7

@@ -47,8 +47,8 @@ The following table lists common multiples of bytes.
 .It Zettabyte Ta ZB Ta 2^70 Ta 10^21
 .It Yottabyte Ta YB Ta 2^80 Ta 10^24
 .It Ronnabyte Ta RB Ta 2^90 Ta 10^27
-.It Quettabyte Ta QB Ta 2^100 Ta 10^30.
-El
+.It Quettabyte Ta QB Ta 2^100 Ta 10^30
+.El
 .Pp
 The following table lists common bit rates as a power of ten.
 .Bl -column -offset 2n \

share/man/man9/zone.9

@@ -341,7 +341,7 @@ Create a zone whose items will be synchronized using the
 .Xr smr 9
 mechanism.
 Upon creation the zone will have an associated
-.Dt smr_t
+.Ft smr_t
 structure which can be fetched using
 .Fn uma_zone_get_smr .
 .El