Provide links additional material that might be helpful for interns who are hoping to improve their R skills beyond the initial training. - [x] make the [Resources for R](https://nceas.github.io/datateam-training/reference/resources-for-r.html) it's own section - [x] highlight specific chapters that might be relevant in books eg. Chapter 3 on programming in [Efficient R](https://csgillespie.github.io/efficientR/programming.html) - [x] add ADC training materials http://training.arcticdata.io/materials/
Provide links additional material that might be helpful for interns who are hoping to improve their R skills beyond the initial training.