Automatically generating the link target for each script saves a lot of
time and potential for errors.
Each kind-of-script page now includes a link target for that page, and
also a table of contents.
In-script markers to delimit text for Sphinx extraction now use native
docstring markers from Ruby, which is a lot more elegant in .rb scripts
- and robust, as long as the fisrt docstring is valid .rst!
Because it's not actually that important to the user how a command is
implemented, and the docs should reflect that. This also makes them
easier to write!