Update bugs of 2004/gavin + format/typo checks

There are also documented features that are now in bugs.md as features,
not bugs, but just linking back to the section provided by the author.

The README.md file has been format and typo checked.

The gavin.md file has been format and typo checked.

bugs.md

@@ -2131,6 +2131,12 @@ The current ([Makefile](2004/gavin/Makefile) was modified to try and
 fit into the current IOCCC build environment.
 
 
+### STATUS: INABIAF - please **DO NOT** fix
+
+See [known features in the README.md](2004/gavin/README.md#known-features) for
+things that are not bugs but documented (mis)features.
+
+
 ## 2004 jdalbec
 
 ### STATUS: INABIAF - please **DO NOT** fix