doc: added StakeHub smart contract and methods to the README file #107

Job	Run time
Build debug plugin ($NANOS_SDK, nanos)	31s
Build release plugin ($NANOS_SDK, nanos)	31s
Build debug plugin ($NANOX_SDK, nanox)	31s
Build debug Ethereum app ($NANOS_SDK, nanos)	41s
Build release plugin ($NANOX_SDK, nanox)	36s
Build debug plugin ($NANOSP_SDK, nanosp)	33s
Build debug Ethereum app ($NANOX_SDK, nanox)	49s
Build release plugin ($NANOSP_SDK, nanosp)	31s
Build debug plugin ($STAX_SDK, stax)	31s
Build debug Ethereum app ($NANOSP_SDK, nanosp)	48s
Build release plugin ($STAX_SDK, stax)	33s
Build debug plugin ($FLEX_SDK, flex)	30s
Build debug Ethereum app ($STAX_SDK, stax)	47s
Build release plugin ($FLEX_SDK, flex)	34s
Build debug Ethereum app ($FLEX_SDK, flex)	46s
E2E Tests	12m 24s
	21m 36s

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