cmd/doc: put blank lines around comment for types, etc.
Better layout.
Fixes #10859.
The issue suggests rearranging so the comment comes out
after the methods. I tried this and it looks good but it is less
useful, since the stuff you're probably looking for - the methods
- are scrolled away by the comment. The most important
information should be last because that leaves it on your
screen after the print if the output is long.