Update README for legacy branch #5252

Job	Run time
Get minimum supported rust version	29s
SDK docs - mgmt	12m 18s
Code Style	1m 36s
test AutoRust	2m 37s
SDK docs	1m 34s
SDK docs - svc	3m 56s
Emulator Tests (stable, false)	6m 42s
WASM Tests (stable, false)	2m 6s
Emulator Tests (1.74.0, false)	5m 0s
E2E Tests (stable, false)	49s
WASM Tests (1.74.0, false)	1m 56s
Emulator Tests (nightly, true)	4m 21s
SDK Tests (stable, false)	5m 55s
WASM Tests (nightly, true)	2m 19s
E2E Tests (1.74.0, false)	2m 31s
SDK Tests (1.74.0, false)	6m 0s
E2E Tests (nightly, true)	2m 34s
SDK Tests (nightly, true)	4m 55s
Services Tests (stable, false)	18m 36s
Services Tests (1.74.0, false)	19m 31s
Services Tests (nightly, true, true)	8m 40s
	1h 54m 25s

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