Add LICENSE

[peterdesmet]

Look up what was decided by Exec.

[peterdesmet]

This is the HTML + RDFa version of the license generated by Creative Commons

<a rel="license" href="http://creativecommons.org/licenses/by/4.0/"><img alt="Creative Commons License" style="border-width:0" src="https://i.creativecommons.org/l/by/4.0/88x31.png" /></a><br /><span xmlns:dct="http://purl.org/dc/terms/" href="http://purl.org/dc/dcmitype/Text" property="dct:title" rel="dct:type">Darwin Core</span> by <a xmlns:cc="http://creativecommons.org/ns#" href="http://www.tdwg.org" property="cc:attributionName" rel="cc:attributionURL">Darwin Core Task Group, Biodiversity Informatics Standards (TDWG)</a> is licensed under a <a rel="license" href="http://creativecommons.org/licenses/by/4.0/">Creative Commons Attribution 4.0 International License</a>.<br />Based on a work at <a xmlns:dct="http://purl.org/dc/terms/" href="http://rs.tdwg.org/dwc/" rel="dct:source">http://rs.tdwg.org/dwc/</a>.