Mentioned the possibility of skipping the symlink for new versions of
git-annex. (Probably deserves a test once the new git-annex trickles
down to CI platforms.)
I stopped trying to explain each config parameter here. Rather, the doc
now shows the user how to ask git-annex to describe config parameters
with `--whatelse`.
This commit adds a new subcommand named "gitannex", aka
"git-annex-remote-rclone-builtin" when invoked via a symlink.
This accomplishes milestone 1 from issue #7625: "minimal support for the
external special remote protocol".
Issue #7625