Missing or to clarify the distinct configuration (jestjs#4540)

* Missing `or` to clarify the distinct configuration

* Update Configuration.md

Author: velles

docs/en/Configuration.md

@@ -8,7 +8,7 @@ previous: jest-object
 next: cli
 ---
 
-Jest's configuration can be defined in the `package.json` file of your project, through a `jest.config.js` file or
+Jest's configuration can be defined in the `package.json` file of your project, or through a `jest.config.js` file or
 through the `--config <path/to/js|json>` option. If you'd like to use
 your `package.json` to store Jest's config, the "jest" key should be used on the
 top level so Jest will know how to find your settings: