[Improve Existing Best Practice Guide]: Fix Citation File Template rendering and update authors

Checked for duplicates

Yes - I've already checked

Best Practice Guide Category

Documentation

Best practice guide URL

https://nasa-ammos.github.io/slim/docs/guides/governance/contributions/code-of-conduct/

Describe the improvement

We need to address several issues with the "Citation File Template" best practice guide:

1. There's a rendering problem for the YAML code described under the "Citation File Template" section - the YAML code is not rendering properly and appears as a raw string.

2. The CITATION.cff file has parsing errors that appear from GitHub.com, with messages like "Your CITATION.cff file cannot be parsed. Make sure the formatting is correct." Also, the file is not rendering correctly in a copy/paste manner when clicking the drop-down for the citation in GitHub - an APA or BibTex example of the citation should appear.

3. We should add Cedric David (https://github.com/c-h-david) and Kyongsik Yun (https://github.com/yunks128/) under the authorship section in the guide.

4. The section "Additional Guidance on Scientific Collaboration" should be renamed to "Code of Collaboration" and restructured as a more step-by-step guide of where to place the file and how to work through it, like the other file examples. It should clarify: Where does it go? Do I need to change anything about it?

Open the guide at the linked URL and locate the source for the “Citation File Template” and “Additional Guidance on Scientific Collaboration” sections. Check the YAML and CITATION.cff examples against GitHub rendering and parsing, add the two named authors, and restructure the renamed section around file placement and required edits. Done means the guide renders correctly, the citation file parses and presents usable APA or BibTeX examples, and the requested guidance is present.