Add doc page about the CDI Extension SPI

[benjamin-confino]

This creates a simple page that goes through implementing CDIExtensionMetadata, it links to a pre-existing blogpost to give a step by step guide to creating a user feature that uses CDIExtensionMetadata

[Emily-Jiang]

LGTM! Thanks @benjamin-confino

[dmuelle]

Hi @benjamin-confino - I changed the base to draft since all OL content must go through draft and staging before targeting vNext. Would you also open an issue in the doc repo to track the work and reviews for this doc? Please include a recommendation of where in the navigation it should go (probably Context and Dependency Injection section?). I think we should also look at migrating your blog post for developing a user feature to the documentation.

For details about the OL topic writing/publishing process, see Publishing a new topic in the readme. Thanks!

[benjamin-confino]

@dmuelle I've opened the issue as requested, and you are correct to assume this goes under Context and Dependency Injection

[dmuelle]

to avoid branch conflicts between draft-staging-production, we only update the nav file from a dedicated branch:

https://github.com/OpenLiberty/docs?tab=readme-ov-file#editing-the-docs-navigation

I went ahead and added this entry from the draft-nav branch in #7532

[benjamin-confino]

My bad. I thought "They can work with you to determine the best section of the navigation for your topic and to update the nav.adoc file." meant it went into this branch. I've pulled that out of the PR

[dmuelle]

LGTM