Follow up cleanup to BBR docs

[srampal]

Followup cleanup to prior BBR docs update.

1. Also fix formatting error in the BBR section of the "Getting started guide"
2. Fix formatting error around footnote annotation for BBR in the Serving Multiple GenAI models section
3. Enabled copy-paste feature within mkdocs.yml for inline copy-paste snippets.

Opened a separate issue (#1608) to track 2 more follow up todos from #1498

1. Use the manifest from a versioned tag rather than main branch
2. Potentially add example manifests for another use case (eg BBR without EPP).

[srampal]

Fixed by #1609