docs: "APIデザインガイドライン"を追加 #3096

Job	Run time
actionlint	17s
build-unix-cpp-example (macos-latest, osx-x64-cpu-cpp-shared)	1m 37s
build-unix-cpp-example (ubuntu-latest, linux-x64-cpu-cpp-shared)	1m 31s
build-windows-cpp-example	4m 14s
c-header	47s
rust-integration-test-strategy-matrix	1s
rust-lint	2m 41s
rust-unit-test	3m 41s
shellcheck	12s
validate-cargo-lock	25s
build-and-test-java-api (windows-latest)	5m 51s
build-and-test-java-api (macos-latest)	2m 44s
build-and-test-python-api (windows-latest)	8m 47s
build-and-test-java-api (ubuntu-latest)	3m 8s
build-and-test-python-api (macos-latest)	3m 3s
build-and-test-python-api (ubuntu-latest)	3m 4s
rust-integration-test (macos-12)	2m 14s
rust-integration-test (ubuntu-20.04)	1m 36s
	45m 53s

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