Update supported platforms in README #2

Job	Run time
webcrypto on Linux desktop / Chrome / Firefox	4m 35s
webcrypto on Linux desktop / Chrome / Firefox	4m 35s
webcrypto on Android emulator	20m 26s
webcrypto on Android emulator	20m 26s
webcrypto on iOS emulator (iPhone)	7m 38s
webcrypto on iOS emulator (iPhone)	7m 38s
webcrypto on macOS Chrome	17m 34s
webcrypto on macOS Chrome	11m 19s
webcrypto on Windows Chrome / Firefox	8m 43s
webcrypto on Windows Chrome / Firefox	8m 43s
	1h 51m 37s

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