message: Add TypeScript question to FAQ
diff: # FAQ
  +## Do I have to write plugins in TypeScript?
  +
  +No, you can use JavaScript if you prefer.
  +
  +We want to keep the Backstage core APIs in TypeScript, but don't force it on individual plugins.
  +
  ## Q: Why Material-UI?
  The short answer is that it's what we've been using in Backstage internally.
  