doc: Adds explanation of the '~' character to networking.istio.io/exportTo annotation

[gbucknel]

I couldn't see any explanation of what the '~' character does for this annotation , but it seems like it is supposed to set visibility to nothing:

https://github.com/istio/istio/blob/055e235292052c100688def4bee9c63b3fab830c/pilot/pkg/serviceregistry/kube/conversion_test.go#L305

https://istio.slack.com/archives/C37A4KAAD/p1728324326776739?thread_ts=1728036926.260279&cid=C37A4KAAD

[istio-policy-bot]

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[linux-foundation-easycla]

• ❌ - login: @gbucknel / name: Graham Bucknell . The commit (e4e532a, 0d63a92) is not authorized under a signed CLA. Please click here to be authorized. For further assistance with EasyCLA, please submit a support request ticket.

[istio-testing]

Hi @gbucknel. Thanks for your PR.

I'm waiting for a istio member to verify that this patch is reasonable to test. If it is, they should reply with /ok-to-test on its own line. Until that is done, I will not automatically test new commits in this PR, but the usual testing commands by org members will still work. Regular contributors should join the org to skip this step.

Once the patch is verified, the new status will be reflected by the ok-to-test label.

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[hzxuzhonghu]

Can you add the doc

comma-separated list namespace names can be specified to the above

[gbucknel]

👍

[gbucknel]

Just need to find out who our company's CLA manager is...

[hzxuzhonghu]

/ok-to-test

[istio-testing]

@gbucknel: The following tests failed, say /retest to rerun all failed tests or /retest-required to rerun all mandatory failed tests:

Test name	Commit	Details	Required	Rerun command
release-notes_api	0d63a92	link	false	/test release-notes
gencheck_api	0d63a92	link	true	/test gencheck

Instructions for interacting with me using PR comments are available here. If you have questions or suggestions related to my behavior, please file an issue against the kubernetes-sigs/prow repository. I understand the commands that are listed here.