Update readme

Author: albertyw

README.md

@@ -330,7 +330,7 @@ The `mochify` function returns a Browserify instance. Please refer to the
 
 ## Code coverage with NYC
 
-Install `nyc@14` (v15 is not yet supported!), the `babelify` transform,
+Install `nyc`, the `babelify` transform,
 `@babel/core` and `babel-plugin-istanbul`:
 
 ```bash

lib/chromium.js

@@ -128,7 +128,7 @@ module.exports = function (b, opts) {
         if (text.indexOf('[COVERAGE ') === 0) {
           var nycRootID = process.env.NYC_ROOT_ID;
           if (!nycRootID) {
-            // NYC >v15 does not export a NYC_ROOT_ID so use a "random" uuid instead
+            // NYC >v15 does not export a NYC_ROOT_ID so use a "random" uuid
             nycRootID = '4638ceac-c8d9-411d-9e1f-72755846a221';
           }
           var nycConfig = JSON.parse(process.env.NYC_CONFIG);