docs: updating tox target in contributing doc
The tox targets were updated a while ago, but the
contributing doc was not.
@@ -53,8 +53,8 @@ You can run:
- `tox` to run all existing tox commands, including unit tests for all packages
under multiple Python versions
- `tox -e docs` to regenerate the API docs
-- `tox -e test-api` and `tox -e test-sdk` to run the API and SDK unit tests
-- `tox -e py37-test-api` to e.g. run the API unit tests under a specific
+- `tox -e test-core-api` and `tox -e test-core-sdk` to run the API and SDK unit tests
+- `tox -e py37-test-core-api` to e.g. run the API unit tests under a specific
Python version
- `tox -e lint` to run lint checks on all code
