[docs] Update SIL.rst

[benrimmington]

Follow-up to: #35993 (comment)

View file: docs/SIL.rst#is-unique

[benrimmington]

@swift-ci Please test

[MaxDesiatov]

Thanks for resolving this!

[Teemperor]

Thanks

[swift-ci]

Build failed
Swift Test Linux Platform
Git Sha - f21cd2d

[MaxDesiatov]

@swift-ci please smoke test

[benrimmington]

The swift-ci test (or smoke test) doesn't appear to build the HTML documentation.

CMake Warning at docs/CMakeLists.txt:24 (message):
  Unable to find sphinx-build program.  Not building docs

But I don't know if swift-ci toolchains or nightly snapshots will be broken?

Can the -W option be removed from docs/CMakeLists.txt, so that sphinx-build warnings don't break the entire build?

[MaxDesiatov]

@swift-ci please smoke test Linux platform

[varungandhi-apple]

Can the -W option be removed from docs/CMakeLists.txt, so that sphinx-build warnings don't break the entire build?

I think this should be okay. We don't have warnings as errors turned on for CI either. That said, I don't remember how long building the docs takes and whether it is happening serially or in parallel, so I'm not sure if we should be building the docs in CI by default... (is that what you're suggesting?)

[benrimmington]

I'm not sure if we should be building the docs in CI by default... (is that what you're suggesting?)

No, I'm only suggesting that a broken link in documentation isn't serious enough to justify a complete build failure.

Since the docs_html phase isn't tested by swift-ci, we won't notice the failure until someone reports it.

[varungandhi-apple]

Okay, yeah that sounds reasonable. FWIW, I'm okay with removing the -W.