Remove design and obsolete VDD from codebase (these are release assets)

[skliper]

Checklist (Please check before submitting)

• I reviewed the Contributing Guide.
• I reviewed the CF README.md file to see if the feature is in the major future work.
• I performed a cursory search to see if the feature request is relevant, not redundant, nor in conflict with other tickets.

Is your feature request related to a problem? Please describe.
Design ppt and VDD doc are binary and challenging to manage within actual codebase with little benefit. Updates to either should not impact codebase hash.

Describe the solution you'd like
Remove from codebase, provide as release assets

Describe alternatives you've considered
Transition design material to markdown would support better text-based management, and possibly create a pdf from it to provide as the release asset (and that PDF could still be updated without impacting codebase hash). Or integrate the design material into the Doxygen users-guide (or both, since Doxygen can reference markdown), which generates a pdf as a release asset.

Additional context
None

Requester Info
Jacob Hageman - NASA/GSFC