Improve Chapter 01 reading path

[jules-tth]

Summary

• Replace the placeholder recommended-reading sublesson with a practical operator reading path.
• Cover local docs, distribution docs, core books, upstream project docs, vendor/cloud docs, community sources, standards, and reading notes.
• Add a suggested first reading sequence, 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 check

• Final open-PR file-overlap check for docs/lessons/01_where_to_start/1.13_recommended_reading.md returned no matches immediately before PR creation.