[clang-tools-extra] [clang-doc] fix ASan complaints from passing RepositoryURL as reference (PR #148923)

[Erick Velez via cfe-commits]

evelez7 wrote:

### Merge activity

* **Jul 16, 4:01 PM UTC**: A user started a stack merge that includes this pull request via [Graphite](https://app.graphite.dev/github/pr/llvm/llvm-project/148923).


https://github.com/llvm/llvm-project/pull/148923