chore(release): 0.9.2 (docs) (#9)

chore(release): 0.9.1

Fix:
- toPlainText() rewrite: walk DOM tree node-by-node instead of cheerio .text().
  Resolves excessive whitespace on deeply-nested tables and improves
  inline-sibling spacing.

Documentation:
- New ROADMAP.md separating shipped/considering items from the issue tracker.
- README: add Outlook iOS and Outlook Android to the supported-clients table
  (was missing despite shipping in 0.9.0), refresh the test count badge to 653,
  and add a new "vs other email libraries" comparison covering juice,
  email-comb, mjml, and maizzle with explicit "complementary, not competitor"
  framing. Replaced the inline roadmap with a link to ROADMAP.md.