Append swift-docc-plugin only when needed #131

Job	Run time
Test without Docker / Windows (5.9 - windows-2022)	5m 46s
Test with Docker / Windows (5.9 - windows-2022)	18m 4s
Test without Docker / Windows (6.0 - windows-2022)	5m 4s
Test with Docker / Linux (5.8 - jammy)	25s
Test with Docker / Windows (6.0 - windows-2022)	15m 45s
Test with Docker / Linux (5.9 - jammy)	28s
Test without Docker / Linux (${{ matrix.swift_version }} - ${{ matrix.os_version }})	0s
Test without Docker / Windows (nightly - windows-2022)	6m 7s
Test with Docker / Windows (nightly - windows-2019)	8m 48s
Test with Docker / Linux (5.10 - jammy)	32s
Test without Docker / Windows (nightly-6.1 - windows-2022)	4m 40s
Test with Docker / Windows (nightly-6.1 - windows-2019)	9m 49s
Test with Docker / Linux (6.0 - jammy)	33s
Test with Docker / Linux (nightly-main - jammy)	37s
Test with Docker / Linux (nightly-6.1 - jammy)	33s
Soundness / API breakage check	0s
Soundness / Documentation check	36s
Soundness / Broken symlinks check	5s
Soundness / Format check	0s
Soundness / License headers check	3s
Soundness / Python lint check	5s
Soundness / Unacceptable language check	3s
Soundness / Shell check	33s
Soundness / YAML lint check	3s
	1h 18m 39s

Provide feedback