Reduced the amount of 'OSCAL' references in data type documentation

[david-waltermire]

Committer Notes

Reduced the amount of 'OSCAL' references in data type documentation. This will make it easier to sync the data types between OSCAL and Metaschema documentation.

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Changes to Core Features:

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[aj-stein-nist]

Small useful changes to make the docs even more straightforward. LGTM.