Improve Chapter 01 information sources lesson

[jules-tth]

Summary

• Rewrite the Chapter 01 other information sources lesson around practical Linux operations
• Add a source hierarchy, distro/upstream/vendor guidance, community-source risk checks, and source-note practice
• Add a safe source-evaluation lab and review questions

Verification

• python3 -m mkdocs build --strict
• git diff --check
• find docs -type f -name "*.md" -size 0 -print
• make build

Duplicate prevention

• Checked open PRs for 1.09_other_sources_of_information before implementation and immediately before PR creation; none were open for this file.
• Skipped the prior planned 1.08 slice because PR Improve Chapter 01 authoritative documentation lesson #307 already covers 1.08_other_authoritative_documentation.