WiP: "Keywords" on PubChem content

<p>Work in progress: exploring the creation of groups of chemicals based on PubChem annotation content in the form of &quot;keywords&quot; (the exact term is still a subject of debate ... for the moment keyword is the placeholder). This is a file deposition corresponding to the code base on the <a href="https://git-r3lab.uni.lu/eci/pubchem/-/tree/master/annotations/keywords">ECI GitLab</a> pages to create these files.</p> <p>Part of this work was performed at <a href="https://www.biohackathon-europe.org/">BioHackathon Europe</a> 2020 #BioHackEU20</p>