reword public API to downstream API

.github/pull_request_template.md

@@ -13,7 +13,7 @@ This PR addresses ...
 ## Tasks
 - [ ] update or add relevant tests
 - [ ] update relevant docstrings and / or `docs/` page
-- [ ] Does this PR change the public API? (if not, label with `no-changelog-entry-needed`)
+- [ ] Does this PR change any API used downstream? (if not, label with `no-changelog-entry-needed`)
   - [ ] write news fragment(s) in `changes/`: `echo "changed something" > changes/<PR#>.<changetype>.rst` (see below for change types)
   - [ ] [run `jwst` regression tests](https://github.com/spacetelescope/RegressionTests/actions/workflows/jwst.yml) with this branch installed (`"git+https://github.com/<fork>/stdatamodels@<branch>"`)