MOdified keywords all yaml for tutorials/demo, added "featured"

atomic-charges/learning_atomic_charges.demoinfo.yaml

cluster-x/clusterX-x1.demoinfo.yaml

cluster-x/clusterX-x2.demoinfo.yaml

demos/creedo.demoinfo.yaml

embedding/Embedding.demoinfo.yaml

errorbars/errorbars_html.demoinfo.yaml

ff-fit/FF-fit.demoinfo.yaml

grain-boundary/GB_tutorial_Berlin_2017.demoinfo.yaml

hands-on/hands-on-tutorial.demoinfo.yaml

lasso/LASSO_L0.demoinfo.yaml

nomad-query/nomad-query.demoinfo.yaml

periodic-table/periodic-table.demoinfo.yaml

phase-diagram/phasediagram.demoinfo.yaml

prototype/brprototype3.demoinfo.yaml

sis/sis_cscl.demoinfo.yaml

sisso/sisso-metal-nonmetal.demoinfo.yaml

soap-similiarity/SOAP_similarity.demoinfo.yaml