Add intro and correct typo #186

Job	Run time
Prepare tests	3s
Format	15s
Test (account-id)	28s
Test (balance)	28s
Test (block-number)	29s
Test (block-timestamp)	28s
Test (call-runtime)	26s
Test (caller)	27s
Test (caller-is-origin)	25s
Test (code-hash)	28s
Test (default-accounts)	25s
Test (ecdsa-recover)	26s
Test (gas-left)	25s
Test (hash-bytes)	26s
Test (hash-encoded)	26s
Test (instantiate-contract)	26s
Test (instantiate-contract2)	8s
Test (invoke-contract)	27s
Test (invoke-contract-delegate)	26s
Test (minimum-balance)	26s
Test (own-code-hash)	25s
Test (set-code-hash)	1s
Test (set-contract-storage)	1s
Test (terminate-contract)	1s
Test (transfer)	1s
Test (trasferred-value)	1s
Test (weight-to-fee)	1s
	8m 29s

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