Update installation documentation. #9161

Job	Run time
base-tests (./cli)	4m 3s
benchmark (e10_drive)	4m 41s
examples-rl (e10_drive)	8m 46s
base-tests (./envision)	4m 31s
benchmark (e11_platoon)	3m 13s
examples-rl (e11_platoon)	4m 8s
base-tests (./smarts/core --nb-exec-timeout 65536 --ignore=./smarts/core/tests/test_notebook.py)	8m 9s
base-tests (./smarts/env --ignore=./smarts/env/tests/test_rllib_hiway_env.py)	7m 16s
base-tests (./smarts/env/tests/test_rllib_hiway_env.py)	4m 38s
base-tests (./smarts/sstudio)	4m 2s
base-tests (./smarts/ray)	5m 46s
base-tests (./examples/tests/test_examples.py)	7m 58s
	1h 7m 11s

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