#200 More visible "shift+enter" docs

[Charles Reis]

We received comments at SIGCSE '04 that users were unable to
figure out how to enter multiple line commands in the Interactions
Pane. While other feature requests are under way to improve the
Interactions Pane in this respect, it's also important to make sure
that the documentation for "shift+enter" is more visible in DrJava's
help files.

Notes: this is a good chance for people to get used to updating the
documentation (as described in the developer docs). This is also a
good chance to figure out why newer versions of docbook2html
(like on greenland) generate the wrong names for the output (ie.
no index.html).