strcpy.3: Add some text to emphasize possibility of buffer runs with strcpy()

Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>

man3/strcpy.3

@@ -49,6 +49,8 @@ including the terminating null byte (\(aq\\0\(aq),
 to the buffer pointed to by \fIdest\fP.
 The strings may not overlap, and the destination string
 \fIdest\fP must be large enough to receive the copy.
+.IR "Beware of buffer overruns!"
+(See BUGS.)
 .PP
 The
 .BR strncpy ()