Add .spi.yml so that DocC documentation is generated #14

Job	Run time
Unit tests / Unit tests (swift:5.9-jammy, 5.9, true)	1m 24s
Unit tests / Unit tests (swift:5.10-jammy, 5.10, true)	1m 25s
Unit tests / Unit tests (swift:6.0-jammy, 6.0, true)	1m 27s
Unit tests / Unit tests (swiftlang/swift:nightly-6.0-jammy, nightly-6.0, true)	1m 55s
Unit tests / Unit tests (swiftlang/swift:nightly-main-jammy, nightly-main, true)	1m 56s
Soundness / API breakage check	1m 49s
Soundness / Documentation check	1m 28s
Soundness / Format check	37s
Soundness / Broken symlinks check	5s
Soundness / License headers check	8s
Soundness / Python lint check	5s
Soundness / Shell check	35s
Soundness / Unacceptable language check	5s
Soundness / YAML lint check	6s
Cxx interop / Cxx interop / Linux (5.9)	1m 20s
Cxx interop / Cxx interop / Windows (6.0)	3s
Cxx interop / Cxx interop / Linux (5.10)	1m 18s
Cxx interop / Cxx interop / Windows (nightly-6.0)	3s
Cxx interop / Cxx interop / Linux (6.0)	1m 23s
Cxx interop / Cxx interop / Windows (nightly-main)	2s
Cxx interop / Cxx interop / Linux (nightly-6.0)	1m 44s
Cxx interop / Cxx interop / Linux (nightly-main)	1m 45s
	20m 43s

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