Spring-ai Fix typo in OpenAI implementation name in documentation (fixes #298)

"Fixes a typo in the documentation where 'Sprig AI' is corrected to 'Spring AI' in the OpenAI implementation section."

Comment From: tzolov

@magnet107 thank you for the contribution. However we've restructured the embeddings.adoc page. The PR affected lines doesn't exist anymore. Feel free to review (and correct) the new page content.