chore: Update documentation for custom smart contracts #4319

Job	Run time
docker	2m 22s
build	2m 40s
e2e-test (ethereum, evmconnect, TestEthereumMultipartyE2ESuite, sqlite3, erc20_erc721, true)	6m 37s
e2e-test (ethereum, evmconnect, TestEthereumMultipartyE2ESuite, postgres, erc20_erc721, true)	6m 56s
e2e-test (ethereum, evmconnect, TestEthereumMultipartyE2ESuite, sqlite3, erc1155, true)	6m 43s
e2e-test (ethereum, evmconnect, TestEthereumMultipartyTokensRemoteNameE2ESuite, postgres, erc20_e...	3m 34s
e2e-test (fabric, TestFabricE2ESuite, sqlite3, none, true)	3m 32s
e2e-test (ethereum, evmconnect, TestEthereumGatewayE2ESuite, sqlite3, erc20_erc721, false)	3m 10s
e2e-test (fabric, TestFabricGatewayE2ESuite, sqlite3, none, false)	3m 30s
e2e-test (ethereum, ethconnect, TestEthereumMultipartyE2ESuite, sqlite3, erc20_erc721, true)	6m 23s
e2e-test (ethereum, ethconnect, TestEthereumGatewayLegacyEthE2ESuite, sqlite3, erc1155, false)	3m 6s
	48m 33s

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