Add documentation to constants

Copy the documentation from `sysexits.h` for each constant. Use the
`sysexits.h` license in order to reuse the documentation.

Copied the text from:
https://sourceware.org/git/?p=glibc.git;a=blob;f=misc/sysexits.h;h=37246b6e752fad0122d842bd479b59d127975bb8;hb=HEAD

1 files changed, 80 insertions, 16 deletions

diff --git a/src/sysexits.lisp b/src/sysexits.lisp
index 255d6b3..f5818ed 100644
--- a/src/sysexits.lisp
+++ b/src/sysexits.lisp
@@ -1,33 +1,97 @@
+;;; Copyright (c) 2021  Teddy Wing
+;;; Copyright (c) 1987, 1993
+;;;	The Regents of the University of California.  All rights reserved.
+;;;
+;;; Redistribution and use in source and binary forms, with or without
+;;; modification, are permitted provided that the following conditions
+;;; are met:
+;;; 1. Redistributions of source code must retain the above copyright
+;;;    notice, this list of conditions and the following disclaimer.
+;;; 2. Redistributions in binary form must reproduce the above copyright
+;;;    notice, this list of conditions and the following disclaimer in the
+;;;    documentation and/or other materials provided with the distribution.
+;;; 3. Neither the name of the University nor the names of its contributors
+;;;    may be used to endorse or promote products derived from this software
+;;;    without specific prior written permission.
+;;;
+;;; THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
+;;; ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+;;; IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+;;; ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
+;;; FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+;;; DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
+;;; OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+;;; HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+;;; LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
+;;; OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+;;; SUCH DAMAGE.
+;;;
+;;;	@(#)sysexits.h	8.1 (Berkeley) 6/2/93
+
 (in-package :sysexits)
 
-(defconstant +ok+ 0)
+(defconstant +ok+ 0
+  "Successful termination.")
 
-(defconstant +usage+ 64)
+(defconstant +usage+ 64
+  "The command was used incorrectly, e.g., with the wrong number of arguments,
+a bad flag, a bad syntax in a parameter, or whatever.")
 
-(defconstant +dataerr+ 65)
+(defconstant +dataerr+ 65
+  "The input data was incorrect in some way. This should only be used for
+user's data & not system files.")
 
-(defconstant +noinput+ 66)
+(defconstant +noinput+ 66
+  "An input file (not a system file) did not exist or was not readable. This
+could also include errors like \"No message\" to a mailer (if it cared to catch
+it).")
 
-(defconstant +nouser+ 67)
+(defconstant +nouser+ 67
+  "The user specified did not exist. This might be used for mail addresses or
+remote logins.")
 
-(defconstant +nohost+ 68)
+(defconstant +nohost+ 68
+  "The host specified did not exist. This is used in mail addresses or network
+requests.")
 
-(defconstant +unavailable+ 69)
+(defconstant +unavailable+ 69
+  "A service is unavailable. This can occur if a support program or file does
+not exist. This can also be used as a catchall message when something you
+wanted to do doesn't work, but you don't know why.")
 
-(defconstant +software+ 70)
+(defconstant +software+ 70
+  "An internal software error has been detected. This should be limited to
+non-operating system related errors as possible.")
 
-(defconstant +oserr+ 71)
+(defconstant +oserr+ 71
+  "An operating system error has been detected. This is intended to be used for
+such things as \"cannot fork\", \"cannot create pipe\", or the like. It
+includes things like getuid returning a user that does not exist in the
+passwd file.")
 
-(defconstant +osfile+ 72)
+(defconstant +osfile+ 72
+  "Some system file (e.g., /etc/passwd, /etc/utmp, etc.) does not exist, cannot
+be opened, or has some sort of error (e.g., syntax error).")
 
-(defconstant +cantcreat+ 73)
+(defconstant +cantcreat+ 73
+  "A (user specified) output file cannot be created.")
 
-(defconstant +ioerr+ 74)
+(defconstant +ioerr+ 74
+  "An error occurred while doing I/O on some file.")
 
-(defconstant +tempfail+ 75)
+(defconstant +tempfail+ 75
+  "Temporary failure, indicating something that is not really an error. In
+sendmail, this means that a mailer (e.g.) could not create a connection, and
+the request should be reattempted later.")
 
-(defconstant +protocol+ 76)
+(defconstant +protocol+ 76
+  "The remote system returned something that was \"not possible\" during a
+protocol exchange.")
 
-(defconstant +noperm+ 77)
+(defconstant +noperm+ 77
+  "You did not have sufficient permission to perform the operation. This is not
+intended for file system problems, which should use NOINPUT or CANTCREAT, but
+rather for higher level permissions.")
 
-(defconstant +config+ 78)
+(defconstant +config+ 78
+  "Configuration error.")