chore: Update documentation for custom smart contracts #4320

Job	Run time
docker	2m 19s
build	2m 59s
e2e-test (ethereum, evmconnect, TestEthereumMultipartyE2ESuite, sqlite3, erc20_erc721, true)	7m 2s
e2e-test (ethereum, evmconnect, TestEthereumMultipartyE2ESuite, postgres, erc20_erc721, true)	7m 12s
e2e-test (ethereum, evmconnect, TestEthereumMultipartyE2ESuite, sqlite3, erc1155, true)	6m 59s
e2e-test (ethereum, evmconnect, TestEthereumMultipartyTokensRemoteNameE2ESuite, postgres, erc20_e...	3m 26s
e2e-test (fabric, TestFabricE2ESuite, sqlite3, none, true)	4m 17s
e2e-test (ethereum, evmconnect, TestEthereumGatewayE2ESuite, sqlite3, erc20_erc721, false)	3m 0s
e2e-test (fabric, TestFabricGatewayE2ESuite, sqlite3, none, false)	4m 4s
e2e-test (ethereum, ethconnect, TestEthereumMultipartyE2ESuite, sqlite3, erc20_erc721, true)	6m 40s
e2e-test (ethereum, ethconnect, TestEthereumGatewayLegacyEthE2ESuite, sqlite3, erc1155, false)	2m 57s
	50m 55s

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