[TOS] Short URL for textbook

[Chris Tyler]

I've created a pair of short URLs for the textbook:

	http://teachingopensource.org/textbook

	http://teachingopensource.org/text

Either of these redirect to a trampoline at [[Textbook Redirect]] so we
can easily update it as new versions are released. To start, I've
pointed to the index page of the Wiki version of 0.8, and added an
{{Admon/note}} with links to the other versions.

My purpose in doing this was to provide an easy-to-remember URL that led
to the latest released release, and to provide a single entry point to
that version -- since some folks were finding the wiki version and then
wondering if any other versions were available.

I hope this is useful, please adjust the trampoline as needed.

-Chris