I also cleaned up the installation section and added links to various
competing redo implementations.
The new README.md is basically just link to the docs on
readthedocs.org, and a link to the mailing list.
These docs need a *lot* more work, but this is enough of an improvement
that I'll commit it anyway for now.
No content yet other than man pages. To make the man pages render
nicely in mkdocs, I removed the static %-headers and put the code for
them into default.md.tmp.do instead. That way, the raw input redo-*.md
files will look right in mkdocs.
