Core doc blocks

[tom-tuva]

Describe your changes

Please include a summary of any changes.
Finished updating core_models.yml to use doc blocks for all column descriptions.

How has this been tested?

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Tested locally

Reviewer focus

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Checklist before requesting a review

• I have added at least one Github label to this PR (bug, enhancement, breaking change,...)
• My code follows style guidelines
• (New models) YAML files are categorized by sub folder and models listed in alphabetical order
• (New models) I have added a config to each new model to enable it for claims and/or clinical data
• (New models) I have added the variable tuva_last_run to the final output
• (Optional) I have recorded a Loom to explain this PR

Package release checklist

• I have updated dbt docs
• I have updated the version number in the dbt_project.yml

(Optional) Gif of how this PR makes you feel

Loom link