Document OBA curation workflow for E's, especially chemical entities

[matentzn]

Write this clearer and add to documentation:

1. Receive two column table from GWAS: label and identifier (label optional)
2. Map identifiers to the respective target ontologies.
   • for chemical entities, CHEBI>GOCC>PR>SWISSLIPDS>LIPIDMAPS
     • mapping rules: if mapped ID species-dependent, generalise to species independent
3. Create a table with the original label and identifier columns submitted, and the new identifier plus its labels (four columns).
4. On the ticket, describe the mapping pipeline, especially if generalised for species independence