The website should link Documentation to the docs generated for our most recent stable release.
By providing directory listing (using `htaccess Indexes`) under /doc/, and having two symlinks latest and stable, we can by default link to stable.
The following patch
- adds to the website Makefile the task add-stable-doc
- changes the default documentation link to /doc/stable/
- removes the html redirecting from doc/ --> doc/latest/
- adds directory listing to /doc/ for a simple view of versioned docs available