remove reference to database that is not used

[mauromiguelm]

Thanks Gabriela for spotting this!

summary

• We dont use kegg anymore, the only exception might be if academic users upload kegg, then we could consider refering to database. I would need to check with @murodzhon and @ivokwee if that's possible
• ideally replace kegg with wikipathways/reactome

omicsplayground

git grep -l KEGG
CHANGELOG-full.md
NOTICE.md
RPackageLicenses.txt
components/app/R/ui.R
components/board.clustering/R/clustering_ui.R
components/board.connectivity/R/connectivity_plot_cumEnrichmentPlot.R
components/board.connectivity/R/connectivity_plot_enrichmentGraph.R
components/board.dataview/R/dataview_module_geneinfo.R
components/board.signature/R/signature_server.R
components/board.signature/R/signature_ui.R
components/ui/ui-links.R

omicsplayground-doc

git grep -l KEGG
methods.rst
modules/figures_v3/test_markers.png
modules/mod1_dataview.rst
modules/mod4_DEGSs.rst

playbase

git grep -l kegg
R/compute2-genesets.R
R/pgx-functions.R