Minor documentation issues

[gilch]

I sometimes look over the docs, see a minor problem, and then forget what it was. I'll collect them here so I don't forget.

The style guide has a broken internal link to a header. (To the one thing that isn't a suggestion.)

The style guide still has an example using deftype, even though that was replaced with deftypeonce, which works differently.

The style guide still calls tags "macros" in some places, which isn't consistent enough with the new glossary.