docs: add EnvoyPatchPolicy examples for cluster resources

[thiagomedina]

What this PR does / why we need it:

Adds two examples to the EnvoyPatchPolicy page showing how to customize Envoy Cluster resources with JSONPatch

Which issue(s) this PR fixes:

Fixes #7306

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PR Checklist

• Authorship & ownership: Coding agents / AI assistants are welcome, but I have reviewed every change, understand how and why it works, can explain and maintain it, and take full responsibility for this PR. I have not submitted generated output I do not understand.
• DCO: All commits are signed off (git commit -s). See DCO: Sign your work.
• API agreed first: If this PR contains API changes (changes under /api), the API was discussed and agreed before the implementation. The API change can be in a separate PR, or in the same PR, but the API must be agreed before implementation. N/A if this PR does not contain API changes.
• Required checks pass: make generate gen-check, make lint, and the unit-test/coverage build pass. (Flaky e2e failures are not considered breakages, but gen-check, lint, and coverage MUST pass.)
• Tests added/updated: New/changed code is covered by appropriate tests. N/A if this PR does not contain code changes.
• Docs: User-facing changes update the docs, either in this PR or a follow-up PR. N/A if this PR does not contain user-facing changes.
• Release notes: For any non-trivial change, added a release-note fragment under release-notes/current/<section>/<pr-number>-<slug>.md (see release-notes/current/README.md for sections and naming). N/A if this PR does not contain non-trivial changes.
• Generated files committed: Ran make gen-check and committed the result if API/helm charts/modules changed.
• Scope & compatibility: The PR is reasonably scoped (no unrelated changes) and preserves backward compatibility, or any breaking change is called out above and documented in release-notes/current/breaking_changes/.
• Codex review: Requested a Codex review and addressed all of its comments.
• Copilot review: Requested a Copilot review and addressed all of its comments.

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[zirain]

please fix DCO.

[thiagomedina]

please fix DCO.

@zirain done

[zirain]

@codex review

[chatgpt-codex-connector]

Codex Review: Didn't find any major issues. Keep it up!

Reviewed commit: e46400db4b

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[zirain]

v1.9 released, can you also copy to v1.9?

[thiagomedina]

v1.9 released, can you also copy to v1.9?

sure, it's done
@zirain

[thiagomedina]

Hi @zirain, the check-links step in the docs-lint failed, can you rerun ?

https://github.com/envoyproxy/gateway/actions/runs/32050386572/job/95536675767?pr=9711

> docsy-example-site@0.10.0 _check:links
> echo IMPLEMENTATION PENDING for check-links; echo

IMPLEMENTATION PENDING for check-links

cp tools/hack/get-egctl.sh site/public
===========> Running docs-check ... 
===========> Running docs-check-links ... 
tools/node_modules/.bin/linkinator site/public/ -r --concurrency 25 --retry-errors --retry --retry-errors-jitter --retry-errors-count 5 --skip "opentelemetry.io blog.envoyproxy.io envoyproxy.io/slack ntia.gov nvd.nist.gov github.com jwt.io githubusercontent.com example.com foo.bar.com github.io gnu.org _print canva.com communityinviter.com sched.co sap.com httpbin.org nemlig.com verve.com goteleport.com developer.hashicorp.com www.signal-ai.com v0.1 v0.2 v0.3 v0.4 v0.5 v0.6 v1.0 v1.1 v1.2 v1.3 v1.4" --verbosity error
→ crawling site/public/
[408] site/public/v1.9/tasks/security/jwt-authentication
site/public/v1.9/tasks/traffic/response-override/
  [408] site/public/v1.9/tasks/security/jwt-authentication
ERROR: Detected 1 broken links. Scanned 2513 links in 1344.894 seconds.
make[1]: *** [tools/make/docs.mk:180: docs-check-links] Error 1
make[1]: Leaving directory '/home/runner/work/gateway/gateway'
make: *** [Makefile:18: _run] Error 2
Error: Process completed with exit code 2.

[arkodg]

hey @thiagomedina can we add an example that is not covered by the first class APIs

[thiagomedina]

hey @thiagomedina can we add an example that is not covered by the first class APIs

hey @arkodg, yes
I changed it to an example not covered by the first class APIs

cc @zirain