[DOCS-3880] Add pattern inspector to docs

[maycmlee]

What does this PR do?

Adds info and images about the new pattern inspector feature.

Motivation

DOCS-3880

---

Reviewer checklist

• [ ] Review the changed files.
• [ ] Review the URLs listed in the Preview section.
• [ ] Check images for PII
• [ ] Review any mentions of "Contact Datadog support" for internal support documentation.

[github-actions[bot]]

Preview links (active after the build_preview check completes)

New or renamed files

Modified Files

• https://docs-staging.datadoghq.com/may/add-pattern-inspector/logs/explorer/group