introduce some initial docc files #366

Job	Run time
Java tests (swift:6.0.2 jdk:Corretto os:jammy)	5m 42s
Swift tests (swift:6.0.2 jdk:Corretto os:jammy)	4m 10s
Verify Samples (swift:6.0.2 jdk:Corretto os:jammy)	11m 40s
soundness / API breakage check	0s
soundness / Documentation check	38s
soundness / Unacceptable language check	4s
soundness / License headers check	4s
soundness / Broken symlinks check	5s
soundness / Format check	0s
soundness / Shell check	31s
soundness / YAML lint check	4s
soundness / Python lint check	8s
	23m 6s

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