chore(docs): mention rules_multirun #1552

Job	Run time
matrix-prep-os	1s
matrix-prep-bazelversion	8s
test (ubuntu-latest, 7.1.1, ., true)	2m 17s
test (ubuntu-latest, 7.1.1, ., false)	2m 20s
test (ubuntu-latest, 7.1.1, e2e/wasm, false)	2m 5s
test (ubuntu-latest, 7.1.1, e2e/smoke, true)	18s
test (ubuntu-latest, 7.1.1, e2e/smoke, false)	2m 5s
test (ubuntu-latest, 7.1.1, e2e/assertion, true)	2m 18s
test (ubuntu-latest, 6.4.0, ., true)	2m 18s
test (ubuntu-latest, 6.4.0, ., false)	33s
test (ubuntu-latest, 6.4.0, e2e/wasm, false)	2m 5s
test (ubuntu-latest, 6.4.0, e2e/smoke, true)	12s
test (ubuntu-latest, 6.4.0, e2e/smoke, false)	2m 5s
test (ubuntu-latest, 6.4.0, e2e/assertion, true)	2m 19s
test (macos-13, 7.1.1, ., true)	2m 21s
test (macos-13, 7.1.1, ., false)	2m 24s
test (macos-13, 7.1.1, e2e/smoke, true)	2m 6s
test (macos-13, 7.1.1, e2e/smoke, false)	39s
	28m 34s

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