cited carpentries lesson template

Author: Toby Hodges

CITATION

@@ -4,3 +4,6 @@ Our preferred DOI is http://doi.org/10.5281/zenodo.840129
 
 The latest DOI is:
 [![DOI](https://zenodo.org/badge/89621457.svg)](https://zenodo.org/badge/latestdoi/89621457)
+
+The structure and style of this user guide is derived from [the Carpentries](https://github.com/carpentries)
+lesson template: [![DOI](https://zenodo.org/badge/DOI/10.5281/zenodo.838778.svg)](https://doi.org/10.5281/zenodo.838778)