added links to instructions for inspecting network activity in browsers

Author: rongxin-liu

cs50.dev.md

@@ -167,9 +167,17 @@ If on a corporate or school network that blocks any of the above, you might need
 
 First of all, make sure all the required [domains](https://cs50.readthedocs.io/cs50.dev/#domains) are not blocked by your device or internet environment.
 
-Check that you have a stable internet connection and that your company network is not blocking the connection. If possible, check logging for rejected connections on your device.
+Check that you have a stable internet connection and that your home, school, or company network is not blocking the connection. If possible, check logging for rejected connections on your device.
 
-If you see rejected connections, make sure the domains documented by the `/meta` REST API endpoint are not blocked by your firewall. For more information, see ["REST API endpoints for meta data."](https://docs.github.com/en/rest/meta/meta#get-github-meta-information)
+To inspect network activity in your browser, follow one of these instructions:
+
+* [Chrome](https://developer.chrome.com/docs/devtools)
+* [FireFox](https://firefox-source-docs.mozilla.org/devtools-user/network_monitor/)
+* [Safari](https://developer.apple.com/documentation/safari-developer-tools/inspecting-safari-macos)
+
+If you see rejected connections, make sure the domains documented by the `/meta` REST API endpoint are not blocked by your firewall. Again, in other words, none of [these domains](https://cs50.readthedocs.io/cs50.dev/#domains) should be blocked.
+
+Optional: For more information, see ["REST API endpoints for meta data."](https://docs.github.com/en/rest/meta/meta#get-github-meta-information)
 
 You can run this command in your terminal to get the list of domains required by GitHub Codespaces: