[Doc] Add github links for source code references

[russellb]

Previously, the use of sphinx.ext.viewcode generated new pages that
included the raw source code. This change adds the
sphinx.ext.linkcode extension, which allows defining a custom method
for generating source code URLs given a code reference. This now
includes links to the appropriate file and line number on github for
code references.

For now I left the viewcode extension in place. The result is that
code references now have 2 [source] links - one for the copy of the
source in the docs, and one to github. If the github links seem to
work well enough, we can drop viewcode later.

Signed-off-by: Russell Bryant [email protected]

[github-actions]

👋 Hi! Thank you for contributing to the vLLM project.
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🚀

[DarkLight1337]

Hmm, the links don't work inside PR builds. I think we should fallback to main branch in this case.

[russellb]

Hmm, the links don't work inside PR builds. I think we should fallback to main branch in this case.

good catch! I'll fix this. I'll also see if I can make it work for PR builds properly.

[russellb]

@DarkLight1337 PR build seems to be working now

[DarkLight1337]

Looks good overall. There is still one failing case, vllm.multimodal.MULTIMODAL_REGISTRY: https://vllm--10672.org.readthedocs.build/en/10672/design/multimodal/multimodal_index.html#registry

[russellb]

Looks good overall. There is still one failing case, vllm.multimodal.MULTIMODAL_REGISTRY: https://vllm--10672.org.readthedocs.build/en/10672/design/multimodal/multimodal_index.html#registry

Thanks. I just improved this one. It's a link to the class MultiModalRegistry instead of the specific instance of that class, MULTIMODAL_REGISTRY, because inspect raises an exception if you pass it an instance of a class. This isn't perfect, but it's better than what it did before with a totally broken link.

[DarkLight1337]

It works now, thanks for spending the time and effort on polishing this!