fix: typo in option definition (#758)

Author: hkdnet

lib/config-util.js

@@ -47,7 +47,7 @@ Config.buildYargs = function (cwd) {
       alias: 'r',
       describe: 'coverage reporter(s) to use',
       default: 'text',
-      globa: false
+      global: false
     })
     .option('report-dir', {
       describe: 'directory to output coverage reports in',