Fix 2004/gavin/img/fs.tar

Now contains old hint file (which is a copy of README.md) and the
updated README.md file. This makes it match correctly. This has not yet
been removed from the todo file as other things are also being removed
from the todo file and I'd rather do those changes together as a single
commit of things completed.

Minor update to thanks file wrt this entry.

thanks-for-help.md

@@ -2708,16 +2708,17 @@ entry](https://gavare.se/ioccc/ioccc_gavare.c.html).
 
 ## <a name="2004_gavin"></a>[2004/gavin](/2004/gavin/gavin.c) ([README.md](/2004/gavin/README.md]))
 
-[Yusuke](#yusuke) provided the `kernel` and `fs.tar` files which can be used if you cannot
-normally use this entry. Instead of generating the files just use the files
-provided, found under the [img/](/2004/gavin/img/) directory. Note that the
-`img/fs.tar` extracts into `fs/` so you will have to fix the tarball; this is
-done this way to prevent extraction from the entry directory overwriting the
+[Cody](#cody) provided the [alt code](/2004/gavin/README.md#alternate-code) for
+those who want to use QEMU. The most important part of this is the macro `K` has
+to be defined as `1`, not `0`.
+
+[Yusuke](#yusuke) provided the `kernel` and `fs.tar` files which can be used if
+you cannot normally use this entry. Instead of generating the files just use the
+files provided, found under the [img/](/2004/gavin/img/) directory. Note that
+the `img/fs.tar` extracts into `fs/` so you will have to fix the tarball; this
+is done this way to prevent extraction from the entry directory overwriting the
 files and causing `make clobber` to wipe some of them out.
 
-Cody provided the [alt code](/2004/gavin/README.md#alternate-code) for those who
-want to use QEMU. The most important part of this is the macro `K` has to be
-defined as `1`, not `0`.
 
 
 ## <a name="2004_jdalbec"></a>[2004/jdalbec](/2004/jdalbec/jdalbec.c) ([README.md](/2004/jdalbec/README.md))