message: Fix mermaid plugin config inclusion
  Config changed a lot while adding piwik
diff: module.exports = { "root": "./protocol-spec" };
  +module.exports["plugins"] = ["mermaid-gb3"];
  // Only add piwik if we're building on the CI and deploying
  if (process.env.CI) {
  - module.exports["plugins"] = ["piwik", "mermaid-gb3"];
  + module.exports["plugins"].push("piwik");
  module.exports["pluginsConfig"] = {
  "piwik": {
  "URL": "apps.nonpolynomial.com/p/",
  