Add support for multiple OpenID providers with role policies (#14223)

- When using multiple providers, claim-based providers are not allowed. All
providers must use role policies.

- Update markdown config to allow `details` HTML element

.github/workflows/markdown-lint.yaml

@@ -25,4 +25,6 @@ jobs:
     - name: Lint all docs
       run: |
         npm install -g markdownlint-cli
-        markdownlint --fix '**/*.md' --disable MD013 MD040
+        markdownlint --fix '**/*.md' \
+          --config /home/runner/work/minio/minio/.github/markdown-lint-cfg.yaml \
+          --disable MD013 MD040