Is there a full reference or documentation for the Quandl R library?

Yes. Please see here to access documentation for the Quandl R package. Please see the following links as well: 

• Installation of Quandl R package and Authentication
• Using the Quandl R package with time-series data
• Using the Quandl R package with tables data

Note that data on Quandl comes in two formats:  time-series and tables. You can learn more about these formats here.