fop(1), fop.1: update to use libdelimit

docs/fop.1

@@ -11,10 +11,9 @@ fop \(en field operator
 .SH SYNOPSIS
 
 fop
-.RB ( -d )
-.RB [ delimiter ]
-.RB index 
-.RB program...
+.RB [ -d\ delimiter ]
+index program
+.RB [ arguments... ]
 .\"
 .SH DESCRIPTION
 
@@ -26,8 +25,17 @@ Performs operations on specified fields in data read from the standard input.
 Sets a delimiter by which the input data will be split into fields. The default
 is an ASCII record separator.
 .\"
+.SH DIAGNOSTICS
+in the event of an error, a debug message will be printed and the program will
+exit with the appropriate sysexits.h(3) error code.
+.\"
 .SH CAVEATS
 
+If the specified index does not exist in the data, the program
+will print all data to the standard output before exiting with an error. If
+input data is not delimited by the specified delimiter, the program will fill
+memory with the contents of the stream before it is output.
+
 Field indices are zero-indexed, which may be unexpected behavior for some users.
 .\"
 .SH RATIONALE