Fix some section references.

share/man/man4/termios.4

@@ -353,8 +353,8 @@ the
 and
 .Dv KILL
 characters (see the
-.Sx "Special Characters section" ) ,
-is received.
+.Sx "Special Characters"
+section), is received.
 This processing affects data in the input queue that has not yet been
 delimited by a newline
 .Dv NL ,
@@ -508,7 +508,7 @@ When a process writes one or more bytes to a terminal device file, they
 are processed according to the
 .Fa c_oflag
 field (see the
-.Sx "Output Modes
+.Sx "Output Modes"
 section).
 The
 implementation may provide a buffering mechanism; as such, when a call to

share/man/man9/BUS_SETUP_INTR.9

@@ -91,7 +91,7 @@ that will not execute any potentially blocking operation, use the
 .Fa filter
 argument.
 See the
-.Sx "Filter Routine" 
+.Sx "Filter Routines"
 section below for information on writing a filter.
 Otherwise, use the
 .Fa ithread
@@ -101,7 +101,7 @@ will be called with the value
 .Fa arg
 as its only argument.
 See the
-.Sx "ithread Routine" 
+.Sx "ithread Routines"
 section below for more information on writing an interrupt handler.
 .Pp
 The

usr.bin/fstat/fstat.1

@@ -136,7 +136,7 @@ or there is an error.
 In this case the remainder of the line does not
 correspond to the remaining headers -- the format of the line
 is described later under
-.Sx Sockets .
+.Sx SOCKETS .
 .It Li MOUNT
 If the
 .Fl n