Openeo-aggregator

- Start with `openeo-aggregator` docs, hosted with GitHub Pages at https://open-eo.github.io/openeo-aggregator/ ([#142](https://github.com/Open-EO/openeo-aggregator/issues/142))

- Also support `job_options_update` to inject job options in synchronous processing requests ([135](https://github.com/Open-EO/openeo-aggregator/issues/135), eu-cdse/openeo-cdse-infra#114)

- Pass through original API errors on synchronous or batch processing ([121](https://github.com/Open-EO/openeo-aggregator/issues/121))

- Add config option `process_allowed` to include/exclude processes ([137](https://github.com/Open-EO/openeo-aggregator/issues/137))

- Remove deprecated `collection_whitelist` config ([139](https://github.com/Open-EO/openeo-aggregator/issues/139))

- Add backend-aware collection allow-list option ([139](https://github.com/Open-EO/openeo-aggregator/issues/139))