Update language to match CEDS

[CJ-Gilbert-CEPI]

Describe the bug

In the Usage Notes for the elements listed below, there are references to elements that do not exist in CEDS. Perhaps these were old proposed names that didn't make it into the model? Or perhaps they are elements that exist in other models?

Credential Definition Category Type has a reference in the Usage Notes to the "Achievement entity" and directs users to "SEE 'Achievement Category System'"
https://ceds.ed.gov/element/000892

Credential Definition Category System has a reference in the Usage Notes to "Achievement Category Type"
https://ceds.ed.gov/element/001245

Expected behavior
The usage note should be revised to either refer to the appropriate CEDS element OR to make it clear which model is being referenced.