updated readme file

README.md

@@ -12,3 +12,17 @@ npm i && npm run serve // run with static server
 
 npm i && npm start // run locally
 ```
+
+### About error boundary
+
+- It is a error handling concept for React component layer [Answer for `what`]
+- For avoid getting page crash on UI, especially during the page rendering or when user interacts with our UI [Answer for `why`]
+- Able to collect error information and display the fallback UI
+- `componentDidCatch` is a good life cycle method to log the error information or update error tracker state when error detected
+
+### About feature flag
+
+- It is a software development technique, which allows to control feature availability [Answer for `what`]
+- When we need to test some features in certain environment (eg: `dev environment`) or for certain type of users (eg: `admin`) [Answer for `why`]
+- Good for release process, especially when feature is not confident to be released, we can hold the feature and before decision has been made (Simple explanation: `ship features safely`)
+- Sometimes, we might consider <a href="https://www.split.io/blog/feature-flags-as-a-service/" target="_blank">feature flag as a service</a>, for example, we might consider to use it for A/B testing?

src/components/FeatureFlagDemo/CompositionDemo.jsx

@@ -15,7 +15,7 @@ export default function CompositionDemo() {
       standard={standard}
       domain={window.location.href}
     >
-      <ErrorBoundaryDemo />
+      <ErrorBoundaryDemo title={"Error Boundary for Composition demo"} />
     </FeatureFlagDemo>
   );
 }

src/components/FeatureFlagDemo/HOCDemo.jsx

@@ -8,7 +8,7 @@ const standard = 0; // for success demo
 
 const HOCDemoComponent = () => (
   <FeatureFlagDemo role={role} standard={standard}>
-    <ErrorBoundaryDemo />
+    <ErrorBoundaryDemo title={"Error Boundary for HOC demo"} />
   </FeatureFlagDemo>
 );