Fix some typos in README.md (facebook#4286)

Author: apaatsio

packages/react-scripts/template/README.md

@@ -562,7 +562,7 @@ No clashes from other `.error` class names
 <button class="Button_error_ax7yz"></div>
 ```
 
-**This is an optional feature.** Regular html stylesheets and js imported stylesheets are fully supported. CSS Modules are only added when explictly named as a css module stylesheet using the extension `.module.css`.
+**This is an optional feature.** Regular html stylesheets and js imported stylesheets are fully supported. CSS Modules are only added when explicitly named as a css module stylesheet using the extension `.module.css`.
 -->
 
 ## Post-Processing CSS
@@ -1565,7 +1565,7 @@ Note that tests run much slower with coverage so it is recommended to run it sep
 
 #### Configuration
 
-The default Jest coverage configuration can be overriden by adding any of the following supported keys to a Jest config in your package.json.
+The default Jest coverage configuration can be overridden by adding any of the following supported keys to a Jest config in your package.json.
 
 Supported overrides:
  - [`collectCoverageFrom`](https://facebook.github.io/jest/docs/en/configuration.html#collectcoveragefrom-array)