update README

README.md

@@ -171,21 +171,24 @@ Separated metadata file (Already included in the above HTML and compressed, it c
 ```
 
 ## View Trace Online 
-> The [Trace Viewer](https://trace.playwright.dev/) requires that the trace file must be loaded over the http:// or https:// protocols without [CORS](https://developer.mozilla.org/en-US/docs/Glossary/CORS) issue, try following start a local web server:
+> The [Trace Viewer](https://trace.playwright.dev/) requires that the trace file must be loaded over the http:// or https:// protocols without [CORS](https://developer.mozilla.org/en-US/docs/Glossary/CORS) issue.
+- Start a local web server with following CLI:
 ```sh
 # serve and open report
 npx monocart show-report <path-to-report>
 
 # serve report
 npx monocart serve-report <path-to-report>
 ```
-It works with `http://localhost:port/` or `http://127.0.0.1:port/`, but to successfully load from other `IP` or `domain`, you must start web server with `https`:
+The server add the http header `Access-Control-Allow-Origin: *` to [allow requesting from any origin](https://developer.mozilla.org/en-US/docs/Web/HTTP/Headers/Access-Control-Allow-Origin), it works with `http://localhost:port/` or `http://127.0.0.1:port/`
+- To successfully work with other `IP` or `domain`, you can start web server with `https`:
 ```sh
 npx monocart show-report <path-to-report> --ssl <path-to-key,path-to-cert>
-# For example: npx monocart show-report test-results/index.html --ssl ssl/key.pem,ssl/cert.pem
-# You can create and install local CA with 'mkcert', see: https://mkcert.dev
 ```
-Or customize your own trace viewer url with option `traceViewerUrl`
+For example: `npx monocart show-report test-results/index.html --ssl ssl/key.pem,ssl/cert.pem`
+
+You can create and install local CA with [mkcert](https://mkcert.dev)
+- Using your own trace viewer url with option `traceViewerUrl`:
 ```js
 // reporter options
 {