better labels for info. urls

[joe]

in show_details, for an instrument, we may have URLs for provider/observatory/instrument, but they're not clearly labeled, and they may not be apparent from the URLs themselves.

Also, there may be times when an instrument doesn't have a page that collects all of the necessary information to do science with the data, and it may be useful to provide for labeling the individual URLs.

(eg, the NRL folks have asked for a link to their database, for anyone who might want to perform searches on SECCHI data that isn't possible through VSO's interface ... this might require making the URLs more apparent from the VSO, as they're somewhat hidden right now)