docs: replace from mapCoverage to collectCoverage in Jest sample. (#493)

Author: potato4d

docs/en/guides/testing-SFCs-with-jest.md

@@ -48,8 +48,7 @@ Next, create a `jest` block in `package.json`:
     "transform": {
       // process `*.vue` files with `vue-jest`
       ".*\\.(vue)$": "<rootDir>/node_modules/vue-jest"
-    },
-    "mapCoverage": true
+    }
   }
 }
 ```
@@ -159,7 +158,7 @@ Jest recommends creating a `__tests__` directory right next to the code being te
 
 Jest can be used to generate coverage reports in multiple formats. The following is a simple example to get started with:
 
-Extend your `jest` config (usually in `package.json` or `jest.config.js`) with the [`collectCoverage`](https://facebook.github.io/jest/docs/en/configuration.html#collectcoverage-boolean) option, and then add the [`collectCoverageFrom`](https://facebook.github.io/jest/docs/en/configuration.html#collectcoveragefrom-array) array to define the files for which coverage information should be collected. You'll also want [`mapCoverage`](https://facebook.github.io/jest/docs/en/configuration.html#mapcoverage-boolean) to be `true`, for coverage data to be accurate.
+Extend your `jest` config (usually in `package.json` or `jest.config.js`) with the [`collectCoverage`](https://facebook.github.io/jest/docs/en/configuration.html#collectcoverage-boolean) option, and then add the [`collectCoverageFrom`](https://facebook.github.io/jest/docs/en/configuration.html#collectcoveragefrom-array) array to define the files for which coverage information should be collected.
 
 ```json
 {
@@ -169,8 +168,7 @@ Extend your `jest` config (usually in `package.json` or `jest.config.js`) with t
     "collectCoverageFrom": [
       "**/*.{js,vue}",
       "!**/node_modules/**"
-    ],
-    "mapCoverage": true
+    ]
   }
 }
 ```