Update gateways namespace from istio-system to istio-ingress

[carlo-zhang]

The document page should be HTTP instead of http2 and namespace. In the installation document of the new version, the gateways are installed under the istio ingress namespace instead of the istio system.

Please provide a description for what this PR is for.

And to help us figure out who should review this PR, please put an X in all the areas that this PR affects.

• [ ] Configuration Infrastructure
• [x] Docs
• [ ] Installation
• [ ] Networking
• [ ] Performance and Scalability
• [ ] Policies and Telemetry
• [ ] Security
• [ ] Test and Release
• [ ] User Experience
• [ ] Developer Infrastructure

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[istio-testing]

Hi @carlo-zhang. 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.

I understand the commands that are listed here.

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/test-infra repository.

[carlo-zhang]

第一次提交，并不是太懂

[craigbox]

Thank you for your contribution! This patch is OK; I can take it from this branch to master.

[zirain]

通常来说你需要将MR提交给master分支，如果有需要的话，审核人会加上cherry-pick标签，cherry-pick到指定的版本

带有如下标记的页面通常包含有对应的测试脚本保证文档的正确性

在修改markdown内容后，你需要本地运行 make gen && make lint，如果可以的话，保证修改后测试用例通过。 比如本地运行 TEST_ENV=kind ADDITIONAL_CONTAINER_OPTIONS="--network host" make doc.test.profile_none 确认是否有错误。

[ericvn]

/ok-to-test

[istio-testing]

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

Test name	Commit	Details	Required	Rerun command
gencheck_istio.io_release-1.14	5e9cfb21ff92a0a300d792bd535799feb33695c4	link	true	/test gencheck_istio.io_release-1.14

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/test-infra repository. I understand the commands that are listed here.

[ericvn]

@carlo-zhang You still need to do a make gen to pick up the additional file changes (snippets).

[ericvn]

This PR is targeted for the release-1.14 branch which will shortly be archived and likely not archived again. Thus this PR will not show up in the 1.14 version of the documentation. This PR should be rebased on the main branch (and cherry-picked to 1.15 if needed).

[ericvn]

Closing this PR since it's against a branch which doesn't typically see updates. https://github.com/istio/istio.io/pull/12315 may solve this issue as well.