Fact-check and style guide updates for V1-to-V2 migration docs

- migrate-v1-v2.md: Fix DRS 2.1 -> DRS 2.2 (latest recommended), remove
  orphaned duplicate text, apply 16 style guide fixes (active voice,
  present tense, V1/V2 casing, descriptive links, second person)
- retirement-faq.md: Verify 8 factual claims, apply 13 style guide fixes
  (ms.topic, descriptive links, TLS/SSL terminology, bold subheadings)

AB#499266

Author: mbender-ms