chore(docs): mention rules_multirun #1553

Job	Run time
matrix-prep-os	1s
matrix-prep-bazelversion	3s
test (ubuntu-latest, 7.1.1, ., true)	5m 27s
test (ubuntu-latest, 7.1.1, ., false)	2m 38s
test (ubuntu-latest, 7.1.1, e2e/wasm, false)	4m 12s
test (ubuntu-latest, 7.1.1, e2e/smoke, true)	2m 26s
test (ubuntu-latest, 7.1.1, e2e/smoke, false)	17s
test (ubuntu-latest, 7.1.1, e2e/assertion, true)	4m 59s
test (ubuntu-latest, 6.4.0, ., true)	2m 52s
test (ubuntu-latest, 6.4.0, ., false)	5m 56s
test (ubuntu-latest, 6.4.0, e2e/wasm, false)	2m 45s
test (ubuntu-latest, 6.4.0, e2e/smoke, true)	18s
test (ubuntu-latest, 6.4.0, e2e/smoke, false)	2m 26s
test (ubuntu-latest, 6.4.0, e2e/assertion, true)	5m 26s
test (macos-13, 7.1.1, ., true)	4m 5s
test (macos-13, 7.1.1, ., false)	3m 33s
test (macos-13, 7.1.1, e2e/smoke, true)	2m 52s
test (macos-13, 7.1.1, e2e/smoke, false)	37s
	50m 53s

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