[Doc] Clarify README install and quick start guidance #316

Job	Run time
build-and-test / build (24.X, x64, humble)	8m 39s
build-and-test / build (24.X, x64, rolling)	13m 35s
build-and-test / build (25.X, x64, jazzy)	8m 42s
build-and-test / build (24.X, x64, jazzy)	8m 15s
build-and-test / build (25.X, x64, humble)	6m 51s
build-and-test / build (25.X, x64, kilted)	7m 43s
build-and-test / build (25.X, x64, rolling)	13m 38s
build-and-test / build (24.X, x64, kilted)	7m 21s
	1h 14m 44s

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