docs: fix case jest to Jest (#183)

Author: ChangJoo-Park

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

@@ -150,7 +150,7 @@ Then configure it in `package.json`:
 
 ### Placing Test Files
 
-By default, jest will recursively pick up all files that have a `.spec.js` or `.test.js` extension in the entire project. If this does not fit your needs, it's possible [to change the testRegex](https://facebook.github.io/jest/docs/en/configuration.html#testregex-string) in the config section in the `package.json` file.
+By default, Jest will recursively pick up all files that have a `.spec.js` or `.test.js` extension in the entire project. If this does not fit your needs, it's possible [to change the testRegex](https://facebook.github.io/jest/docs/en/configuration.html#testregex-string) in the config section in the `package.json` file.
 
 Jest recommends creating a `__tests__` directory right next to the code being tested, but feel free to structure your tests as you see fit. Just beware that Jest would create a `__snapshots__` directory next to test files that performs snapshot testing.