docs: Add openapi as a known word to the project dictionary

[stevenj]

Description

cat-data-service did not spellcheck properly.
openapi is not a known word.

Related Issue(s)

None

Description of Changes

Add it to the project dictionary.

Breaking Changes

None

Please confirm the following checks

• My code follows the style guidelines of this project
• I have performed a self-review of my code
• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation
• My changes generate no new warnings
• I have added tests that prove my fix is effective or that my feature works
• New and existing unit tests pass locally with my changes
• Any dependent changes have been merged and published in downstream module