Update the straightedge-cli section of Validating page

[chrishobcroft]

https://github.com/heystraightedge/straightedge-node/wiki/Validating still talks about edgeware-cli

I understand that @sunnya97 has fixed the npm straightedge-cli at https://npmjs.com/package/straightedge-cli - so we should include this.

Can someone either update this, or add me to the repo so that I can PR it? @bneiluj

Thanks