Consider the use of `themes` extension for ontologies and vocabularies

[fmigneault]

@fmigneault cloned issue crim-ca/mlm-extension#34 on 2024-08-30:

🚀 Feature Request

Add a best practices section about the use of https://github.com/stac-extensions/themes in combination with https://github.com/stac-extensions/classification and MLM.

🔉 Motivation

In some situations, "uncontrolled" names are not sufficient to describe the classes or concepts being described or represented by a model. To provide this context, the https://github.com/stac-extensions/themes extension can be used, which the corresponding themes property as defined by OGC API - Records.

The best practices section should refer to this extension to motive its application by users describing a model with MLM, to ensure the concepts are tied properly in the STAC ecosystem.

📡 Alternatives

Directly use themes from OGC API - Records.