yt-dlp-ejs: add example to notes

Author: aeiouaeiouaeiouaeiouaeiouaeiou

net/yt-dlp-ejs/Portfile

@@ -57,9 +57,12 @@ if {${os.major} <= 16} {
     depends_run-append path:bin/qjs:quickjs
 
     notes "
-    if you are using MacOS 10.12 or older, you will need to pass the
-    '--js-runtimes quickjs' flag or add the appropriate changes to
-    your yt-dlp configuration file.
+    If you are using macOS 10.12 or older, you will need to pass the
+    '--js-runtimes quickjs:${prefix}/bin/qjs' flag or add the appropriate
+    changes to your yt-dlp configuration file. For example, you can run
+    this command to set up the default configuration file:
+
+    echo --js-runtimes quickjs:${prefix}/bin/qjs >> ~/yt-dlp.conf
     "
 }