rose documentation: improve resource links and style

The resource files pointed to in the documentation need some improvements in style. Links to them can fail under certain servers (relative links such as <samp>../etc/</samp> do not always work).

The files have been moved so that the links now work, and the style is improved. Some old files that weren't used have been deleted.

A new cylc suite.rc highlighting library has been added, to finish things off.

@arjclark, please review.