fix: do not reference out-of-date pages

[wesleyboar]

Overview

Do not maintain, reference, nor link to:

• https://designsafe-ci.org/user-guide/usecases/dataanalyticsusecases/
• https://designsafe-ci.org/user-guide/usecases/geohazardusecases/
• https://designsafe-ci.org/user-guide/usecases/seismicusecases/
• https://designsafe-ci.org/user-guide/usecases/windstormsurgeusecases/

Changes

• documented new way to add use cases
• deleted archived reference to old pages

Changes Reverted or Done Outside this PR

• fixed styles to not assume all cards are links
• changed card links to card articles

Testing

• Verify these pages do not exist:
  • http://localhost:8000/user-guide/usecases/dataanalyticsusecases/
  • http://localhost:8000/user-guide/usecases/geohazardusecases/
  • http://localhost:8000/user-guide/usecases/seismicusecases/
  • http://localhost:8000/user-guide/usecases/windstormsurgeusecases/
• Review Use Cases README.md step 12.

UI

Skipped.

[wesleyboar]

Comments for reviewers.

[wesleyboar]

@silviamazzoni, do you still want this change? See video in "UI" section of description.

[silviamazzoni]

I honestly can't remember what this is about....

[wesleyboar]

UI change reverted. This is now an instruction update and a cleanup. Safe. Merging.