TKE-60: add language tags to docs code fences

[wenjiehs]

Closes TKE-60

Summary

• Added info strings to 88 previously unlabeled Markdown code fences under src/content/docs.
• Used text for prose examples, diagrams, logs, formulas, command output, and prompt transcripts.
• Used yaml for the two nominalConcurrencyShares YAML fragments.
• Preserved command content and cloud-operation guidance; no semantic documentation changes.

Doc Change Report

• Source issue: TKE-60 (dbd76570-ffca-415a-9ba2-b517af075bb0)
• Modified scope: user-facing docs under src/content/docs only, 23 Markdown files.
• canonical_doc_path: N/A, broad Markdown syntax hygiene sweep rather than one operation document.
• operation_id: N/A.
• Fact sources: issue acceptance criteria and repository Markdown content. No Tencent Cloud API/product facts changed; official page update time N/A.
• Source adoption reason: the change is syntax annotation only, based on each fenced block's existing content.
• Out of scope: 18 unlabeled fences remain outside the scoped docs tree (.codebuddy, root CONTRIBUTING.md, and tmp).

Static Compile

• Markdown fence scanner: src/content/docs has 0 remaining unlabeled opening fences.
• git diff --check: passed.
• MkDocs strict build: skipped; no mkdocs.yml or mkdocs.yaml exists in the repo.

Dry Run Compile

• npm install --no-package-lock: completed for local verification only.
• npm run build: passed, 193 pages built.
• Cookbook py_compile: skipped; no cookbook Python files changed.

Live Verify

• Not required. This is a Markdown syntax-only change and does not create, update, or delete Tencent Cloud/TKE resources.

Remaining Human Confirmation

• None for this scoped docs pass.

[wenjiehs]

Closing as duplicate of #69, which already covers TKE-60 with the full Markdown fence sweep and required Doc Change Report.