Create Skills Library documentation

[newkek]

Added a new Skills Library documentation page outlining how to create and use reusable skills for AI agents in Datadog.

What does this PR do? What is the motivation?

Adds Skills Library page in public documentation.

Merge readiness

• Ready for merge

AI assistance

Used Codex to generate the page, based off of the dogfooding announcement email, additional instructions and contribution guidelines

[github-actions]

Preview links (active after the build_preview check completes)

New or renamed files

• https://docs-staging.datadoghq.com/newkek/add-skills-library-docs/bits_ai/skills_library

[newkek]

/review

[github-actions]

🤖 Automated review by Claude. AI-generated; verify before acting.

One blocker: the reference link for the Datadog MCP Server points to /bits_ai/mcp_server/, which doesn't exist (the actual page is at /mcp_server/, mounted under the Essentials section — see hugo/config/_default/menus/main.en.yaml:1265 and how bits_ai/_index.md:30 already links it as /mcp_server/). Same broken path appears in further_reading and in the reference-style link definition.

Also: this new public page isn't wired into hugo/config/_default/menus/main.en.yaml, so it won't appear in the side-nav. Add an entry (something like identifier: bits_ai_skills_library, parent: bits_ai, url: bits_ai/skills_library) alongside the other bits_ai children around line 1594–1612.

Content, structure, and Vale style all look clean otherwise.

_{Reviewed 63b80f866402594b8d95cdaca77ec55b5b79ef95 — workflow run}

[newkek]

/review

[github-actions]

🤖 Automated review by Claude. AI-generated; verify before acting.

One grammar blocker in the Availability section, plus a few minor nits.

_{Reviewed 7e183ec09edef6b057a6407985066673b7bdbd1a — workflow run}