Update test_network.md
Update test_network.md

Typo fix on the example code

Signed-off-by: Kaan Oguzhan <a1c0332041e35693a59143d0c49ed17ac9d62383@siemens.com>

manish-sethi/fabric-sidedb,jimthematrix/fabric,hyperledger/fabric,stemlending/fabric,manish-sethi/fabric-sidedb,manish-sethi/fabric-sidedb,stemlending/fabric,manish-sethi/fabric-sidedb,hyperledger/fabric,manish-sethi/fabric,stemlending/fabric,manish-sethi/fabric,manish-sethi/fabric-sidedb,stemlending/fabric,manish-sethi/fabric-sidedb,jimthematrix/fabric,manish-sethi/fabric-sidedb