Add: READMEを追加 #347

Job	Run time
validate-cargo-lock	33s
shellcheck	12s
rust-lint	2m 43s
actionlint	15s
build-and-test-java-api (windows-latest)	9m 30s
build-and-test-java-api (macos-latest)	3m 23s
build-unix-cpp-example (macos-latest, osx-x64-cpu-cpp-shared)	2m 36s
build-and-test-java-api (ubuntu-latest)	2m 46s
build-windows-cpp-example	6m 1s
build-unix-cpp-example (ubuntu-latest, linux-x64-cpu-cpp-shared)	1m 41s
c-header	49s
build-and-test-python-api (windows-latest)	9m 1s
rust-unit-test	6m 19s
rust-integration-test-strategy-matrix	1s
build-and-test-python-api (macos-latest)	8m 2s
build-and-test-python-api (ubuntu-latest)	4m 0s
rust-integration-test (windows-2019, directml)	2m 41s
rust-integration-test (macos-11)	2m 28s
rust-integration-test (ubuntu-20.04)	2m 0s
	1h 5m 1s

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