describe which entailment regime is used

the markdown docs or ideally metadata in the ontology itself would describe what entailment strategy was used to materialize entailments

for example, this query only has asserted D+Rs

```sparql
SELECT ?x ?d ?r ?v0 ?v1 ?v2 WHERE {
?x .
?x ?d .
?x ?r .
OPTIONAL {
?x ?v0} .
OPTIONAL {
?d ?v1} .
OPTIONAL {
?r ?v2}}
```

I think we should coordinate OMO, Robot, and Ubergraph here. Ideally each NG would be annotated with something like prov but minimally a simple vocabulary telling me e.g Elk was used

Start by reviewing the markdown docs and the ontology metadata approach mentioned in the issue. Compare how OMO, ROBOT, and Ubergraph currently represent materialized entailments, and determine whether a simple vocabulary or PROV-style annotation is appropriate. Done means the entailment regime and tool used, such as ELK, are documented or represented consistently.

Written by the indexing model from the issue text.