message: Document hosting_signup config option in source
diff: @@ -296,6 +296,22 @@ export default class UserMenu extends React.Component<IProps, IState> {
  )
  } else if (signupLink || hostingSignupOptions) {
  let hostingSignupIFrame;
  + /*
  + Config schema:
  +
  + ```
  + "hosting_signup": {
  + // URL to load iframe from.
  + "url": "https://prodiver.tld/setup",
  + // Accepted Matrix user server names to show iframe action for.
  + // Subdomains will also match.
  + "domains": [
  + "matrix.org",
  + "domain.tld"
  + ]
  + }
  + ```
  + */
  if (hostingSignupOptions && hostingSignupOptions.url) {
  // If hosting_signup_domains is set to a non-empty array, only show
  // dialog if the user is on the domain or a subdomain.
  