[eslint config] [base] [patch] Include 'accumulator' exception for no-param-reassign

Author: naomiajacobs

packages/eslint-config-airbnb-base/rules/best-practices.js

@@ -173,6 +173,7 @@ module.exports = {
       props: true,
       ignorePropertyModificationsFor: [
         'acc', // for reduce accumulators
+        'accumulator', // for reduce accumulators
         'e', // for e.returnvalue
         'ctx', // for Koa routing
         'req', // for Express requests