Crosswalk between openEO API and OCG API - Processes

[m-mohr]

This document gives a brief overview over the similarities and differences between

• openEO API, v1.2.0
• OCG API - Processes - Part 1: Core, v1.0.0

[jdries]

Maybe important to mention that openEO also defines the actual processes? I know this is not part of the api strictly speaking, but it is the key difference. The other one probably being how processes graphs can be chained and nested.

[m-mohr]

@jdries The process chaining is mentioned in the Process Discovery chapter, but I made it a bit more explicit now. I also added a reference to the pre-defined processes in the same chapter. And there's now a "tl;dr" at the beginnning.

[m-mohr]

See #506

[jdries]

I suggest to raise the point about 'data access' to the level of key differentiators.
Not being able to discover available data collections in a standardized manner is quite a big limitation. It means that an OGC Processes endpoint could expose 'load_collection', but there's no proper way to list available collections.