Fix #275, Remove ppt design and VDD docs from codebase

Checklist (Please check before submitting)

[x] I reviewed the Contributing Guide.
[x] I signed and emailed the appropriate Contributor License Agreement to GSFC-SoftwareRelease@mail.nasa.gov and copied cfs-program@lists.nasa.gov.

Describe the contribution

Testing performed CI - Doc change only

Expected behavior changes None, just paperwork change in that these should be provided as assets on release.

System(s) tested on CI

Additional context Eventually converting to markdown would be good.

Third party code None

Contributor Info - All information REQUIRED for consideration of pull request Jacob Hageman - NASA/GSFC

nasa / CF