clarification on additional motivations for Search API

[mixterj]

The Search API defines a set of possible Motivations (https://preview.iiif.io/api/search-v3-alignment/api/search/2.0/#query-parameters) as well as defines a pattern to using additional motivations from the Web Annotation Ontology. The definition of using other motivations is not clear and should be reviewed for current Search 2.0 Alignment work

[azaroth42]

Previous discussion about changing either params (include / exclude) or the value to allow +/- in the value.

Should just reference the registry of motivations.

[glenrobson]

Existing motivation registry (which is empty):

https://iiif.io/api/registry/motivations/

[tomcrane]

Discussed on Search TSG call 2021-10-19

[digitaldogsbody]

Add new contextualizing motivation to the registry

[kirschbombe]

I have a PR for updating the motivations registry here: #2129.
Should I do the PR against the v3 alignment branch instead?

[kirschbombe]

The motivations registry will be merged shortly. I'll update the v3 branch to just reference the updated registry and to add links for the highlighting and contextualizing motivations to the registry.

[kirschbombe]

I created a new ticket for @azaroth42's comment about changing either params (include / exclude) or the value to allow +/- in the value: #2134