doc: improve documentation for Error.captureStackTrace()

add improvements by @BridgeAR

doc/api/errors.md

@@ -232,31 +232,29 @@ The `constructorOpt` argument is useful for hiding implementation
 details of error generation from the user. For instance:
 
 ```js
-function MyError() {
-  // Set the stack trace limit to zero to avoid calculating the stack trace twice.
+function a() {
+  b();
+}
+
+function b() {
+  c();
+}
+
+function c() {
+  // Create an error without stack trace to avoid calculating the stack trace twice.
   const { stackTraceLimit } = Error;
   Error.stackTraceLimit = 0;
-  const instance = new Error();
+  const error = new Error();
   Error.stackTraceLimit = stackTraceLimit;
-  Error.captureStackTrace(instance, MyError);
-  return instance;
-}
 
-// Without passing MyError to captureStackTrace, the MyError
-// frame would show up in the .stack property. By passing
-// the constructor, we omit that frame, and retain all frames below it.
-new MyError().stack;
-```
-
-We recommend using classes that extend `Error` for custom errors:
+  // Capture the stack trace above function b
+  Error.captureStackTrace(error, b); // Neither function c, nor b is included in the stack trace
+  throw error;
+}
 
-```js
-class MyError extends Error {}
+a();
 ```
 
-Instances of this class are native errors with are instances of `Error` and have
-a correct stack trace.
-
 ### `Error.stackTraceLimit`
 
 * {number}