DOC: run ztunnel in kind not works

[yanickxia]

from this mr #820 merge, seem debug in kind is break.

when start, logs as

2024-04-17T03:12:20.744145Z     warn    xds::client:xds{id=9}   XDS client connection error: gRPC connection error:status: Unknown, message: "client error (Connect)", source: invalid peer certificate: NotValidForName, retrying in 5.12s      

seem server_verifier will check DNS Subject_names, not include 'localhost'

verify_server_name(&cert, server_name)?;
Ok(ServerCertVerified::assertion())

Temporary solution

echo "127.0.0.1 istiod.istio-system.svc" >> /etc/hosts

when start add two env

CA_ADDRESS=https://istiod.istio-system.svc:15012
XDS_ADDRESS=https://istiod.istio-system.svc:15012

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Maybe we should add some reminders to the document. seem not good way to support this case....

[howardjohn]

ISTIOD_CUSTOM_HOST=localhost on istiod also works