The default storage.conf we ship is inconsistent in a few ways;
there's a lot of fixes rolled up into this single commit.

First: we were using a toml "inline table" for the pull options,
and then documenting each key in that table in one blob above.
It simply looks much nicer to use a non-inline table - then
we can move the docs next to each individual value. This is also
more consistent with other sections of the config.

I also thinned out a bit the doc comments; I think instead of trying
to have a longer explanation of zstd:chunked in the comments here
we should refer to the man page, which is a better place to have
details (and that we should fill out more).

Per another PR, I also stumbled across the fact that we have a
lot of "string bool" values and cannot be native TOML booleans. Document
that clearly next to each type.

We already have default values in the *code* for all
of these, so comment them all out to be consistent with other
values. (We're then getting closer to having the config file
be entirely comments, but that's a distinct project)

Finally, update the recent man pages I added to match
these changes.

Signed-off-by: Colin Walters <walters@verbum.org>