Remove member-card folder from origin after archive

The LSBC Member credential on Sovrin MainNet was archived in PR #192,
but the original folder was never deleted from the repository.

This commit:
- Deletes OCABundles/schema/bcgov-digital-trust/member-card/ (Sovrin MainNet)
- Removes the nav entry from mkdocs.yml
- The archived copy remains at _archived/sovrin-mainnet/member-card/

This properly completes the move operation that was started in #190.

Signed-off-by: Kyle Robinson (krobinsonca)
Signed-off-by: Kyle Robinson <kyle.robinson@briartech.ca>

Author: krobinsonca

OCABundles/schema/bcgov-digital-trust/member-card/LSBC-OCA.xlsx

@@ -98,7 +98,6 @@ nav:
           - OCABundles/schema/bcgov-digital-trust/LCRB/selling-it-right-showcase/README.md
           - OCABundles/schema/bcgov-digital-trust/LCRB/serving-it-right-showcase/README.md
           - OCABundles/schema/bcgov-digital-trust/LCRB/special-event-server-showcase/README.md
-        - OCABundles/schema/bcgov-digital-trust/member-card/README.md
         - OCABundles/schema/bcgov-digital-trust/member-card-showcase/README.md
         - BC Mines Act Permit:
           - OCABundles/schema/bcgov-digital-trust/mines-act-permit/0.3/README.md