Update/improve state proof protobuf documentation

### Background

Lets revise the documentation on the state_proof.proto to be more accurate in the defition of merkle path and state proof

### Acceptance Criteria

See above

### Dependencies

_No response_

### Definition of Ready (DoR) Checklist

- [ ] Clear acceptance criteria
- [ ] Clear and detailed description
- [ ] Dependencies identified
- [ ] Links to documentation
- [ ] Should be completable in 2-3 Days
- [ ] Initial draft of Low-level design document
- [ ] At least high level test plan
- [ ] Groomed/Estimated

### Definition of Done (DoD) Checklist

- [ ] Acceptance Criteria complete
- [ ] No Codacy issues greater than minor (in new code)
- [ ] JavaDocs updated/created
- [ ] Code commented
- [ ] Unit tests created/updated
- [ ] 80% test code coverage (in new code)
- [ ] Happy Path and major negative cases in HAPI tests as applicable

Locate state_proof.proto and read its existing documentation for merkle paths and state proofs. Compare the current wording with the intended concepts, then update the comments so both definitions are accurate and clear; the issue is done when the revised documentation reflects those concepts.

Written by the indexing model from the issue text.