Added VERSIONS section; rewote info about linking with -lrt.

man3/shm_open.3

@@ -32,6 +32,8 @@ shm_open, shm_unlink \- Create/open or unlink POSIX shared memory objects
 .BI "int shm_open(const char *" name ", int " oflag ", mode_t " mode );
 .sp
 .BI "int shm_unlink(const char *" name );
+.sp
+Link with \fI-lrt\fP.
 .SH DESCRIPTION
 .BR shm_open ()
 creates and opens a new, or opens an existing, POSIX shared memory object.
@@ -225,6 +227,8 @@ An attempt was to made to
 a
 .I name
 that does not exist.
+.SH VERSIONS
+These functions are provided in glibc 2.2 and later.
 .SH "CONFORMING TO"
 POSIX.1-2001.
 .LP
@@ -232,12 +236,6 @@ POSIX.1-2001 says that the group ownership of a newly created shared
 memory object is set to either the calling process's effective group ID
 or "a system default group ID"
 .SH "NOTES"
-These functions are provided in glibc 2.2 and later.
-Programs using these functions must specify the
-.B \-lrt
-flag to
-.B cc
-in order to link against the required ("realtime") library.
 .LP
 POSIX leaves the behavior of the combination of
 .B O_RDONLY