[clang-tools-extra] [clang-doc] Add a breadcrumb navigation bar (PR #173297)

[Erick Velez via cfe-commits]

evelez7 wrote:

### Merge activity

* **Jan 7, 9:34 PM UTC**: A user started a stack merge that includes this pull request via [Graphite](https://app.graphite.com/github/pr/llvm/llvm-project/173297).


https://github.com/llvm/llvm-project/pull/173297