[tldoc] top-level readme.en.html

[Karl Berry]

I just made some changes to the English readme.en.html file.  However, I
suggest waiting a day or two before updating the translations, since I
rather suspect another tweak or two may end up getting made.  We are
going to have to do another round of binary builds, so it will be a few
days before we can close up shop, anyway.

Also, FYI, there is also now a truly tiny (three lines) top-level README
which just says to look in the readme-*.dir directories.  I don't think
it should be translated, since the whole point was to reduce the number
of files in the root directory.  

Thanks,
Karl