[ajeetdsouza]

Did a quick pass over our docs. This PR:

• Sections of buf.gen.yaml now contain the prefix:

  # You will need to adapt these values to your environment:
  # https://protobufes.com/reference/environments/

• Fixes prose that had drifted from the code
  • CONTRIBUTING pointed to ./manage.mjs test, which doesn't exist; it now says ./manage.mjs ci
  • express tests use the Node.js test runner, not Jasmine
  • remix builds with esbuild (classic Remix compiler), not Rollup
  • vue tests use Vue Test Utils, not Vue Testing Library
  • astro dev runs on port 4321 and svelte preview on port 4173, not 3000
  • bundle-size imports SayRequestSchema and SayVolumeSchema, not SayRequest
  • cloudflare-workers linked to url-shortener.spec.ts; the file is url-shortener.test.ts
• Fixes broken URLs, and updates redirected ones and the upgrade-guide links in CONTRIBUTING to the framework versions we use today
• Fixes a reversed Markdown link in the nextjs README, and moves the react-native Metro section out of the middle of the command list
• Uses bash for all shell blocks, with no $ prompts so it's easier to copy
• Adds minor consistency, formatting, spelling, and grammar fixes