docs(help): add push style monitor help documentation (#1795)

[paultanay]

What's changed?

Added English and Chinese help documentation for the Push Style Monitor (app-push), which was missing from the docs despite the feature being fully implemented.

• home/docs/help/push.md — English doc covering how push works, the correct API endpoint, Prometheus text format, shell/Python/Java examples, and common problems
• home/i18n/zh-cn/.../help/push.md — Chinese translation
• home/sidebars.json — registered help/push under the service category

Part of #1795

Checklist

• I have read the Contributing Guide
• I have written the necessary doc or comment.
• I have added the necessary unit tests and all cases have passed.

Add or update API

• I have added the necessary e2e tests and all cases have passed.

[Aias00]

Review: docs(help): add push style monitor help documentation (#1795)

Verdict: ✅ APPROVED — documentation-only change, accurate and well structured.

What this PR does

• Adds home/docs/help/push.md (English) and the matching home/i18n/zh-cn/.../help/push.md (Chinese) describing HertzBeat's push-style (Prometheus-format) monitoring.
• Registers help/push in home/sidebars.json (and correctly adds the missing trailing comma after help/jenkins).

Assessment

• Content quality: The doc is clear, internally consistent, and covers How-It-Works, endpoint, metrics format, config params, and three language examples (curl/Python/Java) plus a troubleshooting section. EN/ZH parity is good.
• Structural correctness: sidebars.json edit is valid JSON; the new doc id push matches the sidebar reference.
• Risk: None — pure docs, no code path touched.

Minor (non-blocking) suggestions

• The endpoint path POST /api/push/prometheus/job/{job}/instance/{instance} should be confirmed against the actual push controller (not verifiable from this docs-only PR). If the real path differs, both docs would need a fix. Consider cross-linking to the API reference once merged.
• job/instance are documented as [a-zA-Z0-9_] only — worth double-checking this matches the server-side route regex so the "Common Problems" tip is accurate.

No code changes requested. Good contribution.

[Aias00]

thx for your contributon, pls fix ci

[Aias00]

failed again, pls fix.
you can run check locally by the way

[paultanay]

failed again, pls fix. you can run check locally by the way

Identifying the issue. I will let you know when it's done

[paultanay]

Ci passed locally, clould you please check now @Aias00

[Aias00]

LGTM, thx for your contribution~