Multi-Taxonomy Indexing Documentation

[fmendezh]

Create documentation on how GBIF is processing occurrence records using multiple taxonomies, the documentation should mention the following topics:

1. The eXtended release of the Catalogue of Life, what is it? The document should briefly mention that this will replace the GBIF Backbone.
2. GBIF Backbone, mention that it won't be updated, and how we will preserve Backbone identifiers.
3. API: new parameters, download services, API response format.
4. Explain how the name matching is performed against a particular checklist and how that information is later enriched using other datasets (IUCN RedList).
5. Update API docs (if needed).
6. Briefly explain how the new portal is capable of switching between multiple taxonomies.
7. The document must accessible from https://techdocs.gbif.org/en/data-processing/

[djtfmartin]

I think is done, ready for review. Visible on test site only.

[CecSve]

I would like to provide feedback on the text. Would PR for text changes assigned to @djtfmartin be the correct way to go about it?