docs: READMEのビルド周りの記載を更新し、自分でビルドした場合は製品版のVVMが読めないことをわかるように (#840) #2917

Job	Run time
shellcheck	13s
actionlint	21s
rust-integration-test-strategy-matrix	1s
rust-lint	4m 16s
rust-unit-test	4m 55s
validate-cargo-lock	21s
build-and-test-java-api (windows-latest)	5m 17s
build-and-test-python-api (windows-latest)	7m 16s
build-and-test-java-api (macos-latest)	2m 45s
build-and-test-python-api (macos-latest)	3m 7s
build-and-test-java-api (ubuntu-latest)	2m 42s
build-and-test-python-api (ubuntu-latest)	2m 59s
build-unix-cpp-example (macos-latest, osx-x64-cpu-cpp-shared)	1m 33s
c-header	46s
build-windows-cpp-example	3m 52s
build-unix-cpp-example (ubuntu-latest, linux-x64-cpu-cpp-shared)	1m 43s
rust-integration-test (macos-12)	2m 27s
rust-integration-test (ubuntu-20.04)	1m 19s
	45m 53s

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