Format and link fix 2004/arachnid

Fix format of README.md file. I wanted to say that the author is a
sociopath :-) for using 'w', 'a', 's' and 'd' but that's not right in
the README.md (the judges put something amusing there about it anyway)
so I'm doing it here instead. :-) Okay he's not really but the
navigation is difficult to vi users as the judges point out. Still a
very fun game and I didn't get lost!

Fix dead link via Internet Wayback Machine.

Renamed arachnid.info to arachnid.txt. I hope this helps with rendering
later on so that browsers can also view it. There are other entries
where it might have been good to consider this but I did not think of it
at the time.

2004/arachnid/README.md

@@ -1,12 +1,8 @@
 # Best use of Vision
 
-    Nick Johnson
-    25 Harvey Tce
-    Richmond
-    Christchurch
-    New Zealand
-
-    http://www.notdot.net/
+Nick Johnson
+New Zealand
+<https://web.archive.org/web/20051030162356/http://www.notdot.net/>
 
 ## To build:
 
@@ -32,41 +28,42 @@ and then try:
 ./arachnid arachnid.c
 ```
 
-## Judges' remarks
+## Judges' remarks:
 
 The fun part comes when you realize that the maze scrolls.  The overall
 visual effect is quite pleasing (at least on some displays), and, well,
 it's a lot of fun.
 
 Navigation is through the use of the "wasd" inverted-T formation on
-Qwerty keyboards.  Rogue players, vi users, and Dvorak typists are
+QWERTY keyboards.  Rogue players, vi users, and Dvorak typists are
 invited to get lost!
 
-## Author's remarks
+## Author's remarks:
 
 This program accepts ASCII formatted mazes as input, and renders
-them onscreen for the user to explore, complete with Line Of Sight
-- you cannot see parts of the maze your avatar (the '@') could not
+them on screen for the user to explore, complete with Line Of Sight
+\- you cannot see parts of the maze your avatar (the `@`) could not
 have seen.
 
-The maze files will be interpreted with spaces ' ' as gaps, tilde
-'~' symbols (if any) as exits (which get represented as a NetHack
-style '<' once loaded), and any other characters as walls.
+The maze files will be interpreted with spaces `' '` as gaps, tilde
+`~` symbols (if any) as exits (which get represented as a
+[NetHack](https://www.nethack.org) style `<` once loaded), and any other
+characters as walls.
 
-Feed the program its own source for a default maze. Running it with
-no command line parameters will do this. In a nice symmetry, the 
-character constant '~' that recognises exits to input mazes itself 
-forms the exit to the default maze. Another maze, 'maze1' has also 
-been provided. This maze is 255x255, about the largest maze supported, 
-for the particularaly insane maze explorers out there.
+Feed the program its own source for a default maze. Running it with no command
+line parameters will do this. In a nice symmetry, the character constant `~`
+that recognises exits to input mazes itself forms the exit to the default maze.
+Another maze, [arachnid.txt](arachnid.txt) has also been provided. This maze is
+255x255, about the largest maze supported, for the particularly insane maze
+explorers out there.
 
-Usage:
+### Usage
 
 ```sh
 ./arachnid [mazefile]
 ```
 
-You can explore the maze using the w,a,s, and d keys.
+You can explore the maze using the `w`,`a`,`s`, and `d` keys.
 
 ## Copyright and CC BY-SA 4.0 License: