Format and URL fix 2004/gavare

Format fix README.md.

Add humour heading (as 'humor' as the author spelt it wrong :-) :-) )
instead of what was a '<humor>..</humor>'. This due this is not valid
html (guess why! :-) ) and so would not show up right in GitHub (or in
any other html document). Using a '### ...' seemed better than escaping
the <>s.

Dead link. Found new one via the Internet Wayback Machine.

2004/gavare/README.md

@@ -1,11 +1,8 @@
 # Best Use of Light and Spheres
 
-    Anders Gavare
-    Gibraltargatan 82-156
-    SE-412 79 Gothenburg
-    Sweden
-
-    http://www.mdstud.chalmers.se/~md1gavan/
+Anders Gavare  
+Sweden  
+<https://gavare.se>
 
 ## To build:
 
@@ -29,11 +26,11 @@ make
 
 For users of systems that distinguish between text and binary mode
 (you know who you are), add a library call that specifies binary mode
-for stdout as the first statement of main(),
-or use freopen("ioccc_ray.ppm", "wb", stdout) and do not use redirection.
+for stdout as the first statement of `main()`,
+or use `freopen("ioccc_ray.ppm", "wb", stdout);` and do not use redirection.
 
 A freely distributable command-line version of Microsoft Visual C
-exhibits an optimizer bug when compiling this entry. Disable /Og for
+exhibits an optimizer bug when compiling this entry. Disable `/Og` for
 best results.
 
 The judges were able to figure out how to control position
@@ -51,8 +48,8 @@ directives.
 
 The program is a small ray-tracer. The first line of the source code may
 be modified if you want the resulting image to be of some other resolution
-than the predefined. The 'A' value is an anti-alias factor. Setting it to
-1 disables the anti-aliasing feature (this makes the output look bad), but
+than the predefined. The `A` value is an anti-alias factor. Setting it to
+`1` disables the anti-aliasing feature (this makes the output look bad), but
 setting it too high makes the trace take a lot more time to complete.
 
 The ppm image can then be viewed using an image viewer of your own choice.
@@ -60,18 +57,18 @@ The ppm image can then be viewed using an image viewer of your own choice.
 so be patient.)
 
 I am very much aware about the fact that I'm breaking the guidelines. For
-example, the word 'int' is a reserved word and therefore all variable
+example, the word `int` is a reserved word and therefore all variable
 declarations are implicit.  There will no doubt be _lots_ of warnings,
 no matter which compiler is used.  Still, the source code should be word-
-length-independent and endianess-independent.
+length-independent and endianness-independent.
+
+### Humor
 
-<humor>
 Another reason for writing code without using reserved words is that many
 text editors will make all reserved words turn BOLD when printed on
 paper.  Since I care for the global environment, we shouldn't waste any
 more laser toner, or ink, than necessary. Everyone should write C code
-with no  reserved words, and our world will be a better place.
-</humor>
+with no reserved words, and our world will be a better place.
 
 ## Copyright and CC BY-SA 4.0 License: