clang: Package docs related to clang-doc tool

[kraj]

Fixes ERROR: clang-19.0.0-r0 do_package: QA Issue: clang: Files/directories were installed but not shipped in any package: /usr/share/clang-doc /usr/share/clang-doc/clang-doc-default-stylesheet.css /usr/share/clang-doc/index.js

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