message: backend: add ROLLBAR_ACCOUNT_TOKEN to readme
diff: @@ -29,6 +29,7 @@ AUTH_GOOGLE_CLIENT_ID=x AUTH_GOOGLE_CLIENT_SECRET=x \
  AUTH_GITHUB_CLIENT_ID=x AUTH_GITHUB_CLIENT_SECRET=x \
  AUTH_OAUTH2_CLIENT_ID=x AUTH_OAUTH2_CLIENT_SECRET=x \
  AUTH_OAUTH2_AUTH_URL=x AUTH_OAUTH2_TOKEN_URL=x \
  +ROLLBAR_ACCOUNT_TOKEN=x \
  SENTRY_TOKEN=x \
  LOG_LEVEL=debug \
  yarn start
  